UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


THE  ALMOND  IN  CALIFORNIA 


BY 
R.  H.  TAYLOR 


BULLETIN  No.  297 

August,  1918 


UNIVERSITY   OF  CALIFORNIA  PRESS 

BERKELEY 

1918 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPEKIMENT  STATION  STAFF 

HEADS  OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director ;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Mter  E.  Jaffa,  Nutrition. 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 
{Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kellet,  Agricultural  Chemistry. 

H.  J.  Quatle,  Entomology. 

J.  B.  Davidson,  Agricultural  Engineering. 

Elwood  Mead,  Rural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

W.  L.  Howard,  Pomology. 
|Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 

O.  J.  Kern,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Rogers,  Olericulture. 

J.  G.  Moodey,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

DIVISION  OF  POMOLOGY 
W.  L.  Howard  W.  L.  Sweet 

R.  II.  Taylor  G.  L.  Philp 

A.  H.  Hendrickson  }V.  W.  Hoffman 

*E.  L.  Overholser  M.  N.  Wood 

W.  P.  Tufts 


t  In  military  service. 

f  In  co-operation  with   office  of  Public   Roads  and   Rural   Engineering,   U.    S. 
Department  of  Agriculture. 

*  Exchange  professor   from   Cornell   University   for    1918-19. 


THE  ALMOND  IN  CALIFORNIA 

By  R.  H.  TAYLOR 


INTRODUCTION 

The  almond  (Prunus  communis)  is  supposed  to  be  native  to  the 
countries  around  the  Mediterranean  and  at  present  the  bulk  of  the 
world's  supply  is  produced  in  that  region.  It  resembles  the  peach 
somewhat  in  manner  of  growth  and  character  of  blossoms  and  leaves, 
but  the  wood  is  much  harder  and  the  tree  is  longer-lived  under  equally 
favorable  conditions.  The  fruit,  instead  of  having  a  thick,  fleshy 
pericarp  as  in  the  case  of  the  peach,  has  a  thin,  leathery  pericarp  or 
hull,  which  splits  on  ripening  and  generally  opens  when  dry,  exposing 
the  nut  inside. 

California  produces  over  98  per  cent  of  the  entire  American  crop 
and  has  done  so  for  many  years.  During  the  period  from  1900  to 
1913  the  number  of  bearing  trees  remained  approximately  the  same, 
new  plantings  having  replaced  old  orchards  that  were  being  pulled 
out.  The  variation  in  California  production  from  year  to  year  prior 
to  1915,  as  shown  in  figure  1,  is  due  to  seasonal  variations  rather  than 
to  change  in  acreage. 

Imports  into  the  United  States  from  the  Mediterranean  countries 
are  also  shown  in  figure  1,  the  top  line  representing  the  total  imports, 
the  other  lines,  as  indicated,  showing  the  proportion  of  that  total  orig- 
inating in  the  three  principal  countries  exporting  to  the  United  States. 
Previous  to  1912  the  records  of  shelled  and  unshelled  almonds  were 
not  kept  separate.  Since  the  records  have  been  segregated,  the  per- 
centages of  shelled  almonds  imported  each  year  have  been  approxi- 
mately as  follows : 

Per  cent 

1912-13 83 

1913-14 70 

1914-15 71 

1915-16 82 

1916-17 79 

Average 77 

With  the  1915  crop  the  production  in  California  entered  upon 
what  appears  to  be  a  long  prospective  increase.  The  large  acreage 
of  almonds  set  out  in  the  last  four  or  five  years  is  the  result  of  greatly 
improved  market  conditions  due  to  the  successful  work  of  the  Cali- 


4  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

fornia  Almond  Growers'  Exchange.  The  first  of  these  new  plantings 
are  now  coming  into  bearing,  and  each  year  for  many  years  in  the 
future  will  continue  to  see  increased  yields.  Large  acreages  are  still 
being  planted  so  that  the  almond  production  in  California  bids  fair 
to  continue  to  grow. 

Within  the  next  few  years  California  growers  will,  in  all  prob- 
ability, be  forced  to  accept  lower  prices  for  their  almonds  than  they 
are  now  receiving.  The  American  markets  are  fully  supplied  at 
present  prices,  yet  constantly  increasing  acreage  will  inevitably  result 
in  a  greatly  increased  tonnage.  European  almonds  are  being  pro- 
duced at  a  lower  net  cost  and  can  be  laid  down  on  the  Atlantic  Coast 
more  cheaply  than  is  possible  with  the  California  product.  This 
brings  the  grower  face  to  face  with  the  necessity  of  becoming  more 
thoroughly  familiar  with  the  most  economical  methods  of  production 
and  marketing  if  they  are  to  continue  to  make  a  profit.  It  is  essential, 
therefore,  that  a  careful  study  be  made  of  all  the  factors  concerned 
in  the  growth,  production  and  final  disposition  of  the  almond  crop. 

HABITS 

The  almond  is  the  first  of  the  deciduous  fruit  trees  to  start  growth 
and  come  into  bloom  in  the  spring,  and  normally  the  last  one  to  shed 
its  leaves  in  the  fall.  In  other  words,  it  has  a  very  short  period  of 
rest.  "When  the  trees  are  forced  into  premature  dormancy  by  mites 
or  lack  of  moisture,  they  soon  reach  the  end  of  their  normal  rest 
period  before  the  winter  season  is  over.  Then  the  first  warm  weather 
in  spring  will  bring  the  trees  into  blossom.  In  some  cases  where 
moisture  and  temperature  conditions  are  favorable  late  in  the  fall, 
they  may  actually  blossom  before  the  winter  season.  In  young  trees 
that  have  become  dormant  unusually  early,  the  rest  period  may  term- 
inate and  then  the  tips  of  the  branches  resume  growth  and  continue 
to  slowly  develop  new  leaves  at  the  terminals  throughout  the  winter. 
Trees  which  have  been  kept  growing  thriftily  until  the  leaves  have 
been  forced  to  fall  by  the  cold  weather  and  frosts  of  winter,  do  not 
tend  to  blossom  as  early  in  the  spring,  nor  do  they  open  under  the 
influence  of  a  few  days  of  warm  weather  in  late  winter  or  early  spring. 

Young  trees  blossom  somewhat  later  than  the  older  trees,  and  buds 
on  sucker  growth  blossom  later  than  the  more  mature  portions  of  the 
same  tree.  The  difference  may  amount  to  three  or  four  days  or  almost 
a  week.  Well-grown  trees  carry  large  numbers  of  blossoms  over  the 
entire  tree,  as  shown  in  figure  2. 

The  wood  of  the  almond  is  very  hard  and  strong,  enabling  the  tree 
to  bear  the  weight  of  heavy  crops  where  pruning  has  been  given  proper 


THE   ALMOND    IN    CALIFORNIA 


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6  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

attention  during  the  formative  period  of  the  young  tree.  As  with 
other  fruit  trees,  the  almond  is  subject  to  heart-rot  and  care  should 
always  be  exercised  to  prevent  the  checking  and  cracking  of  large 
wounds  and  consecpient  infection  with  decay  organisms.  The  hard- 
ness of  the  wood  makes  it  the  finest  kind  of  fuel,  and  when  old  orchards 
are  being  dug  up  the  returns  from  the  sale  of  wood  often  more  than 
pay  for  the  expense  of  digging  and  cutting  up  the  trees  and  burning 
the  brush. 

The  nuts  are  of  two  general  classes — sweet  and  bitter  almonds. 
The  former  is  primarily  the  almond  of  commerce,  though  the  latter 
is  used  largely  in  the  manufacture  of  almond  oil  and  almond  flavoring, 
as  well  as  in  the  manufacture  of  prussic  acid.  The  bitter  almond  is 
also  used  largely  in  nurseries  as  a  rootstock  upon  which  to  bud  the 
almond  and  some  other  fruits. 

For  a  long  time  there  has  been  considerable  evidence  to  show  that 
some  varieties  are  always  self -sterile  while  a  few  are  sometimes  self- 
fertile.  Work  done  in  1916  and  1917  by  Tufts1  shows  that  practically 
all  varieties  are  self-sterile  and  that  some  of  the  self-sterile  varieties 
are  also  inter-sterile.  In  these  tests  the  principal  commercial  varieties 
were  used.  Blossoms  of  each  variety  were  pollenized  with  pollen  from 
its  own  blossoms  and  from  each  of  the  others.  Checks  were  for 
natural  pollination  with  each  variety.  The  important  results  of  this 
work  are  briefly  summarized  as  follows : 

The  Nonpareil  and  I.X.L.  are  inter-sterile,  although  both  are  inter- 
fertile  with  the  Ne  Plus  Ultra. 

The  Languedoc  and  Texas  are  inter-sterile. 

The  I.X.L.  and  Peerless  are  practically  inter-sterile. 

The  California  has  proved  the  best  pollenizer  thus  far  tested,  for 
all  varieties  that  bloom  near  it. 

The  Drake  is  inter-fertile  with  the  Nonpareil,  I.X.L.,  Ne  Plus 
Ultra,  Peerless  and  Jordan,  the  only  ones  tested. 

The  I.X.L.  is  inter-fertile  with  the  Drake,  Jordan,  California, 
Languedoc,  Ne  Plus  Ultra  and  Texas. 

The  Ne  Plus  Ultra  is  inter-fertile  with  the  California,  Drake, 
I.X.L.,  Languedoc  and  Nonpareil. 

REQUIREMENTS 

While  the  almond  is  in  many  ways  an  easy  tree  to  grow  where 
conditions  are  favorable,  it  is  more  particular  in  its  requirements  than 
most  common  orchard  fruits,  and  the  grower  may  find  it  difficult  to 


1  Tufts,  W.  P.,  unpublished  data  from  experiments  conducted  in  the  Univer- 
sity Farm  orchard,  at  Davis,  California. 


Til  10   ALMOND   IN    CALIFORNIA 


■y.  .> 


1 


^MBMB^^^HI^HBBmMBB^M 


Fig.  2. — Seven-year-old  Ne  Plus  Ultra  almond  in  full  bloom,  at  the  University 
Farm,  March,  1915,  showing  distribution  of  blossoms  well  down  into  center  of 
tree.     Paper  bags  cover  blossoms  pollenized  by  hand. 


8  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

produce  a  good,  thrifty  tree  unless  he  chooses  the  proper  location. 
Very  often  it  will  grow  well  and  make  a  fine  healthy  tree,  but  owing 
to  unfavorable  conditions,  will  not  bear  regularly,  if  it  all. 

CLIMATE 

Heat. — Where  the  conditions  of  soil  and  moisture  are  favorable 
the  almond  will  endure  the  intense  heat  of  the  interior  valleys  and 
even  of  the  Imperial  Valley,  provided  it  is  pruned  properly  to  shade 
the  main  branches  so  as  to  prevent  sunburn.  Where  trees,  by  severe 
pruning,  are  opened  up  suddenly  to  the  intense  heat  of  the  summer 
sun,  almonds  will  sunburn,  but  if  the  necessary  opening  up  is  clone 
gradually,  the  bark  will  become  inured  to  the  new  conditions  without 
danger.  The  nuts  grow  and  ripen  more  satisfactorily  in  the  greater 
heat  of  the  interior  than  along  the  coast. 

Frost. — The  almond  tree  is  hardy  and  will  endure  fully  as  much 
cold  as  the  hardiest  peach  without  injury.  Trees  are  found  growing 
well  in  Illinois,  Ohio,  New  York  and  other  Eastern  states.  In  very 
favorable  seasons  they  may  even  bear  fruit,  though  this  happens  very 
seldom,  clue  to  the  extremely  early  habit  of  blooming  before  the  spring 
frosts  are  over.  The  first  warm  weather  seems  to  start  the  trees  into 
bloom,  especially  where  the  enforced  dormant  season  of  winter  is  very 
long. 

The  blossoms,  on  the  other  hand,  are  very  tender.  There  is  a  great 
range  in  the  degree  of  frost  which  will  cause  injury,  depending  largely 
on  the  condition  of  the  tree  during  the  time  that  the  fruit  buds  are 
forming  and  developing,  as  well  as  on  the  duration  and  severity  of 
the  frost.  Buds  and  blossoms  on  trees  which  have  been  forced  into 
premature  dormancy,  either  by  lack  of  moisture  or  by  severe  attacks 
of  red  spider,  are  much  more  susceptible  to  frost  than  those  on  trees 
which  have  continued  growth  late  enough  in  the  fall  to  provide  for 
the  proper  development  and  maturity  of  the  buds.  After  differentia- 
tion of  fruit  buds  commences  in  the  summer,  the  almond  leaves  should 
remain  on  the  tree  until  late  into  the  fall  in  order  to  strengthen  and 
develop  the  fruit  buds  and  store  up  the  elaborated  food  material  for 
the  use  of  the  buds  in  their  normal  development  through  the  winter. 
Studies  of  almond  buds  gathered  from  healthy  trees  which  held  their 
leaves  until  late  fall  frosts  at  Davis,  showed  the  first  evidence  of 
differentiation  between  fruit  and  flower  buds  commencing  about 
August  18,  while  the  flower  was  not  completely  developed  until 
February  18  following.  During  the  intervening  time  development 
proceeded  unchecked  through  the  winter  even  though  the  tree  was 
apparently  dormant.     During  the  time  the  crop  is  ripening  on  the 


THE   ALMOND   IN    CALIFORNIA  9 

trees,  little  is  done  toward  storing  food  material  for  the  buds.  If  the 
leaves  turn  yellow  or  drop  soon  after  harvest,  the  trees  do  not  have 
the  opportunity  of  storing  a  sufficient  supply  of  plant  food  for  their 
normal  requirements  and  the  buds  an;  insufficiently  nourished  during 
the  winter  period.  The  resulting  buds  are  weakened  and  the  indi- 
cations are  that  they  are  unable  to  endure  unfavorable  climatic 
conditions  in  the  spring,  such  as  light  frosts,  continued  cold  weather 
or  sudden  changes  from  warm  to  cold  weather. 

The  most  tender  stage  in  the  blossoming  and  development  of  the 
young  fruit  seems  to  be  immediately  following  the  dropping  of  the 
calyx  lobes  from  the  young  fruit  as  it  first  commences  to  swell  rapidly. 
The  blossom  becomes  more  and  more  tender  as  it  opens  out  and  reaches 
the  above  stage.  After  the  young  fruit  has  attained  the  size  of  a  pea 
it  rapidly  becomes  more  resistant  to  low  temperatures.  Blossoms  with 
the  petals  exposed  but  not  yet  opened  have  been  known  to  stand  tem- 
peratures of  24  degrees  F.  and  blossoms  with  petals  beginning  to  fall 
have  stood  28  degrees  F.  No  records  are  available  as  to  the  duration 
of  these  temperatures.  In  other  cases,  blossoms  with  the  petals  falling 
have  been  killed  by  temperatures  of  30  and  31  degrees  F.  It  must  be 
remembered  in  this  connection  that  the  almond  blooms  earlier  than 
other  orchard  fruits  and,  therefore,  is  often  subjected  to  much  more 
severe  frosts  than  occur  during  the  blooming  period  of  the  later  fruits. 
The  greatest  injury  is  likely  to  occur  when  a  frost  follows  one  or  more 
days  of  warm  weather.  When  the  mean  temperature  both  day  and 
night  remains  low,  frosts  that  might  otherwise  kill  the  flowers  or 
setting  fruit  do  no  harm.  This  is  what  occurred  in  February,  1917, 
at  the  University  Farm,  when  repeated  frosts  at  blooming  time  did 
no  harm  whatever. 

In  determining  the  desirability  of  a  location  in  regard  to  its 
freedom  from  frost,  the  possibility  of  adequate  air  drainage  is  an 
important  item.  For  this  reason  the  lands  along  the  lower  foothills 
immediately  above  the  floor  of  the  valleys  are  ordinarily  much  less 
subject  to  frost — because  the  cold  air  is  free  to  drain  away  to  the 
lower  levels.  Generally  the  lands  along  the  banks  of  streams  which 
have  been  built  up  higher  than  the  other  lands  of  the  Great  Valleys 
through  which  they  flow,  are  less  subject  to  frost  by  reason  of  the 
natural  flow  of  the  cold  air  from  them  to  the  lower  lands  adjacent. 
For  the  same  reason  the  planting  of  almonds  in  the  lower  lands  of 
the  valleys,  no  matter  how  large  the  valleys  may  be,  should  be  avoided, 
unless  the  locality  has  been  thoroughly  tested  for  a  long  period  of 
years  and  has  proved  to  be  an  exception  to  the  rule  because  of  some 
peculiar  situation  with  favoring  air  currents  or  air  drainage,  such  as 


10  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

might  exist  near  a  natural  draw  in  the  hills  where  the  settling  of  the 
cold  air  in  some  portions  of  the  adjacent  valley  might  be  prevented. 
Such  locations  are  generally  confined  to  very  small  areas.  Oftentimes 
an  opening  or  draw  in  the  hills  may  serve  as  an  outlet  for  the  drainage 
of  much  colder  air  from  considerably  higher  elevations  beyond,  and 
then  the  danger  from  frost  is  very  greatly  increased.  This  is  very 
common  where  canons  act  as  drains  to  conduct  the  cold  air  from  the 
high  Sierras  to  the  valleys  below. 

Variable  weather  conditions,  and  especially  as  regards  temperature 
in  the  spring  after  growth  commences,  are  highly  undesirable.  Warm 
weather  immediately  followed  by  cold  tends  to  produce  sour-sap,  fruit 
drop  and  kindred  physiological  ills.  Oftentimes  crops  have  been  lost 
where  no  frosts  occurred  after  blooming  commenced,  simply  due  to 
sudden  changes  in  the  weather.  However,  it  is  highly  probable  that 
the  greater  portion  of  the  trouble  with  fruit  dropping,  when  of  the 
size  of  peas  or  larger,  is  due  to  improper  pollination.  AVhen  the  soil 
is  not  sufficiently  well  drained  at  such  a  time,  the  sour-sap  effect  is 
greatly  augmented. 

Humidity. — Foggy  or  moist  weather  during  ripening  or  harvest- 
ing is  highly  objectionable.  The  nuts  do  not  dry  out  rapidly  enough 
on  the  trees  to  prevent  the  growth  of  molds  and  consequent  darkening 
of  the  shells.  The  nuts  then  require  much  heavier  bleaching  to 
brighten  them  properly  for  the  demands  of  the  market.  The  damp 
weather  prevents  the  rapid  and  thorough  drying-out  of  the  kernel ; 
the  sulphur  fumes  are  absorbed  by  the  moist  kernel  and  it  sometimes 
becomes  rancid  before  it  is  six  months  old. 

Much  damp  weather  in  the  spring  encourages  the  growth  of  "shot- 
hole"  fungus  in  the  blossoms  and  fruit,  often  causing  the  loss  of  a 
considerable  portion  of  the  crop ;  the  loss  of  leaf  surface  from  the 
fungus  infection  is  sometimes  so  great  as  to  materially  affect  the  vigor 
and  vitality  of  the  tree. 

Kainfall. — It  is  impossible  to  state  any  definite  amount  of  rainfall 
which  will  or  will  not  maintain  the  trees  and  enable  them  to  bear 
regular  crops  of  nuts,  for  so  much  depends  not  only  on  the  variation 
in  rainfall  in  different  sections  and  in  different  years,  as  regards  dis- 
tribution throughout  the  year,  but  also  on  the  time  and  intensity  of 
the  fall,  the  character  of  the  weather  following  the  rains  and  the 
ability  of  the  soil  to  receive  and  retain  the  rain  that  falls.  Ordinarily, 
however,  with  the  above  factors  favorable,  it  is  conceded  that  where 
the  winter  rainfall  averages  sixteen  inches,  almonds  can  generally  be 
grown  without  supplementing  the  water  supply  by  irrigation,  if  the 
orchardist  exercises  reasonable  care  to  conserve  the  moisture  for  the 


THE   ALMOND   IN   CALIFORNIA  11 

use  of  the  trees.  Where  the  rainfall  is  inadequate  some  means  of 
irrigation  must  be  found  to  make  up  the  deficit. 

In  some  sections  the  annual  rainfall  varies  greatly  from  year  to 
year.  Often  it  falls  in  such  a  way  that  a  large  proportion  of  it  is 
lost  in  the  surface  run-off.  In  many  places  the  soil  is  so  leachy  that 
it  is  incapable  of  holding  sufficient  water  for  the  use  of  the  trees 
throughout  the  summer,  much  of  the  winter  rainfall  being  lost  in  the 
underground  drainage.  Under  either  of  these  conditions,  40  inches 
of  rainfall  might  not  be  sufficient.  Very  often  winter  rains  are  fol- 
lowed by  desiccating  winds  so  that  a  considerable  portion  of  the  rain 
which  falls  is  lost  by  evaporation  before  anything  can  be  done  to 
hold  it. 

Continued  rainy,  damp  and  cold  weather  at  the  time  of  blooming 
is  apt  to  sour  the  pollen  or  actually  wash  it  away  and  thus  prevent 
the  fertilization  of  the  blossoms,  without  which  a  crop  is  impossible. 
Bees  and  other  insects  are  the  principal  means  of  accomplishing  the 
pollination  of  almonds  and  such  weather  prevents  them  from  working. 

SOIL 

The  almond  is  a  deep-rooting  tree  and  draws  heavily  upon  the 
plant-nourishing  elements  of  the  soil.  In  ripening  the  large  number 
of  seeds  which  it  is  required  to  do,  the  tree  must  draw  upon  a  con- 
siderable area  of  soil  in  order  to  supply  the  large  amount  of  mineral 
matter  that  is  needed  to  develop  and  mature  the  seeds.  Analyses  of 
almonds,  as  compared  with  other  commonly  grown  fruits  and  nuts, 
made  by  Colby,2  show  that  the  almond  leads  in  the  total  quantity  of 
mineral  matters  withdrawn  from  the  soil.  Colby  further  states  that 
"The  stone  fruits  fall  much  below  the  almond  in  total  ash  (mineral 
matter)  excepting  the  olive,  the  ash  of  which,  however,  is  largely  silica 
(nearly  eight-tenths),  an  ingredient  so  plentifully  distributed  in  all 
soils  that  it  is  of  no  pecuniary  value."  Table  I  illustrates  this  state- 
ment. 

These  figures  suggest  the  necessity  of  having  a  deep,  rich,  well- 
drained  soil  for  best  results.  For  this  reason  and  because  of  the 
deep-rooting  habit  of  the  almond,  the  soil  should  be  at  least  ten  or 
twelve  feet  deep. 

Hardpan.— Compacted  substrata  in  the  soil,  whether  they  be  hard 
clay  layers  or  cemented  layers  of  silicious,  ferruginous  or  calcareous 
origin,  are  objectionable.  They  not  only  prevent  the  roots  from  for- 
aging to  a  considerable  depth  as  they  normally  tend  to  do,  but  they 
prevent  proper  drainage  and  aeration  of  the  soil.     If  such  layers  are 


2  Colby,  Geo.  E.,  Ann.  Eept.  Cal.  Agri.  Exp.  Sta.,  1895-1896  and  1896-1897. 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

TABLE  I 

Soil  Ingredients  Extracted  by  the  Almond  as  Compared  with  Other  Orchard 

Trees,  as  Shown  by  Analysis  of  1000  lbs.  Each  of  the 

Crops  in  a  Fresh  Condition 

Phosphoric  Total 

Potash,  Lime,  Acid,  Ash,  Nitrogen, 

Fruit  lbs.  lbs.  lbs.  lbs.  lbs. 

Almond    (hulled)    5.49  1.72  4.33  15.00  16.40 

Almond    (not   hulled)  ....  9.95  1.04  2.04  17.29  17.01 

Walnut    (hulled)    ....: 1.50  1.81  2.78  7.50  10.20 

Walnut   (not  hulled)  8.18  1.55  1.47  12.98  5.41 

Chestnut    (hulled)    3.72  .71  1.89  8.20  8.00 

Chestnut   (not  hulled)  ....  3.67  1.20  1.58  9.52  6.40 

Prunes    (green)    2.66  .13  .53  4.03  1.48 

Apricots    (green)  2.83  .18  .71  5.16  2.29 

Olives  8.85  2.32  1.18  94.63*  5.85 

*  80.7  pounds  of  which  is  silica. 

comparatively  thin,  that  is,  not  more  that  two  or  three  feet  thick  at 
the  most,  they  may  be  shattered  with  dynamite  so  as  to  allow  the 
moisture,  air  and  roots  to  penetrate  to  the  better  soil  below.  Hardpan, 
therefore,  should  be  avoided  where  it  is  too  thick  to  be  broken  up  or 
where  it  is  not  underlaid  by  desirable  soil. 

Humus. — A  plentiful  supply  of  humus  in  the  soil  is  essential.  It 
not  only  improves  the  physical  condition  of  the  soil,  but  assists  drain- 
age, moisture  retention  and  in  rendering  the  plant  food  available  in 
sufficient  quantities  for  the  use  of  the  trees  and  for  the  maturing  of 
full  crops  of  almonds.  Many  orchards  have  been  very  light  producers 
year  after  year  because  of  a  deficiency  of  humus  in  the  soil. 

Drainage. — The  almond  root  is  very  particular  as  to  its  air  and 
moisture  requirements  in  the  soil.  It  will  not  endure  standing  water 
in  the  soil  for  any  length  of  time,  especially  during  the  growing 
season.  Exclusion  of  air  by  excessive  moisture  is  believed  to  be  one 
of  the  most  productive  causes  of  "sour-sap."  If  allowed  to  continue 
for  any  length  of  time  such  conditions  will  cause  the  death  of  many 
or  even  all  the  roots  and  with  them  the  top. 

Water  Table. — A  factor  which  is  very  commonly  overlooked  in 
connection  with  the  natural  drainage  of  almond  lands  is  the  position 
of  the  water  table  at  different  seasons  of  the  year.  Great  care  must 
be  exercised  in  choosing  a  location  to  be  sure  that  the  water  table  does 
not  rise  during  the  summer.  This  is  a  very  serious  problem  in  many 
irrigated  sections.  Where  the  water  table  during  the  winter  months 
is  less  than  12  feet  in  depth  it  is  highly  desirable  to  have  as  little 
fluctuation  as  possible.  Where  fluctuations  take  place  at  a  greater 
depth  than  12  feet  they  are  not  generally  serious.    The  ideal  condition 


THE   ALMOND   IN   CALIFORNIA  ]3 

is  where  the  water  table  is  highest  in  the  winter  and  quickly  drops 
after  the  winter  rains  are  over,  to  a  depth  of  from  10  to  12  or  15  feet, 
remaining  at  that  point  during  the  remainder  of  the  growing  season. 

The  soil  in  addition  to  being  well  drained,  must  be  sufficiently 
retentive  of  moisture  to  supply  the  tree  throughout  a  long,  dry  grow- 
ing-season. If  the  soil  will  not  retain  a  sufficient  amount  of  the  winter 
and  spring  rains,  recourse  must  be  had  to  irrigation  to  supply  the 
deficiency. 

Alkali. — Alkali  lands  are  unsuited  to  almond  culture  and  should 
be  carefully  avoided. 

In  summarizing  the  soil  requirements  for  almond  culture,  it  may 
be  stated  that  the  ideal  almond  soil  is  a  medium  loam,  uniform  in 
texture,  or  nearly  so,  to  a  depth  of  at  least  twelve  feet,  well  drained 
and  yet  retentive  of  moisture  for  the  use  of  the  tree  during  the  sum- 
mer. Fortunately  some  of  the  best  almond  soils  are  situated  along 
stream  banks  where  the  land  is  relatively  high,  and  is,  therefore,  less 
subject  to  frost.  These  streams  flowing  from  the  mountains  and  foot- 
hills have  built  up  their  own  beds  by  the  detritus  brought  from  the 
hills.  The  coarser  particles  being  deposited  first  and  nearest  the 
stream  itself,  make  the  better  drained  soils,  while  the  finer  particles 
and  the  clays,  deposited  further  back  from  the  bank  and  in  the  lower 
lands,  form  the  heavier  soils. 

The  various  conditions  mentioned  above  are  what  the  tree  should 
have  for  best  conditions  of  growth  and  production.  Oftentimes  these 
conditions  may  be  approached  without  the  soil  being  as  deep  as  ten 
or  twelve  feet.  Exceptions  to  this  will  be  mentioned  in  discussing  the 
various  almond  districts  of  the  state.  It  is  essential  to  understand 
that  trees,  while  growing  and  bearing  on  shallow  soils  in  some  locali- 
ties, do  so  because  of  other  exceptionally  favorable  conditions;  either 
the  soil  is  exceptionally  well  drained  and  yet  sufficiently  retentive  of 
moisture,  or  the  humus  in  the  soil  is  plentiful  and  the  roots  are  able 
to  work  into  the  underlying  partially  decomposed  rock  for  moisture 
and  some  plant  food.  In  such  localities  the  trees  bear  comparatively 
well  because  of  the  exceptional  freedom  from  frost  in  the  spring. 
Trees  in  these  localities  are  generally  smaller  than  on  the  deeper, 
richer  soils,  and  where  other  conditions  are  equal,  they  bear  crops  in 
proportion  to  their  size. 

ALMOND    DISTRICTS 

Almonds  are  grown  in  nearly  every  county  in  California.  In  some 
counties  the  few  trees  growing  only  occasionally  succeed  in  producing 
a  crop  of  nuts.  There  are  sections  in  nearly  all  parts  of  the  state, 
however,  where  they  are  a  success  commercially.     Within  these  see- 


14  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

tions  may  be  found  desirable  and  undesirable  locations,  depending 
upon  soil  and  moisture  conditions  and  freedom  from  injurious  frosts. 
Any  discussion  of  a  district,  therefore,  does  not  necessarily  mean  that 
all  lands  within  that  district  are  uniformly  adapted  to  almond  culture. 
On  this  account  it  is  impossible  to  define  a  district  any  more  closely 
than  to  name  the  center  and  include  with  it  the  outlying  districts. 
In  the  same  way  it  is  sometimes  impossible  to  say  just  where  one 
district  begins  and  another  ends.  Adaptability  of  any  special  location 
can  be  determined  only  by  careful  study  of  the  land  itself  and  diligent 
inquiry  of  those  familiar  with  it. 

As  far  as  possible,  districts  should  be  chosen  where  a  definite  cold 
winter  season  exists.  Warm  weather  and  lack  of  freezing  tempera- 
tures do  not  hold  the  trees  fully  dormant  and  any  frequent  occurrence 
or  unusual  continuation  of  spring  weather  in  the  winter  will  start  the 
trees  into  growth ;  cooler  weather  following,  interferes  with  the  normal 
flow  of  sap,  results  in  injury  to  the  tree  and  blossoms,  and  often  causes 
gumming  of  the  nuts  which  mature.  This  condition  exists  largely  in 
the  lower  elevations  in  Southern  California  and  especially  in  the 
coastal  portion,  where  the  ameliorating  influence  of  the  Pacific  is  felt. 
This  same  condition  exists  close  to  the  coast  in  the  northern  portion 
of  the  state.  Further  inland  and  at  higher  elevations  the  winters  are 
more  pronounced,  and  where  these  are  not  too  severe  or  prolonged  the 
almond  thrives  best. 

SACRAMENTO  VALLEY  AND  FOOTHILL  SECTIONS 

Commencing  in  Solano  County,  about  eight  miles  northwest  of  Sui- 
sun  and  extending  as  far  north  as  the  southern  end  of  Shasta  County, 
close  to  the  base  of  the  foothills  on  the  west  side  of  the  Sacramento 
River,  are  a  large  number  of  orchards  on  the  bottom  lands  of  the 
valley.  These  are  found  principally  on  the  higher  lands  along  the 
banks  of  streams  flowing  from  the  Coast  Range  in  a  generally  easterly 
direction  to  the  Sacramento  River.  The  two  most  important  streams 
of  this  type  are  Putah  Creek,  forming  the  boundary  between  Yolo 
and  Solano  counties,  and  Cache  Creek,  flowing  through  the  Capay 
Valley  and  across  Yolo  County  to  the  Sacramento  River. 

These  plantings  being  on  the  floor  of  the  valley  are  more  subject 
to  frost  than  the  foothill  plantings,  but  they  have  the  advantage  of 
being  on  the  rich  valley  soils,  and  while  they  may  lose  a  crop  occa- 
sionally from  frosts,  they  make  it  up  in  the  long  run  by  the  much 
larger  growth  of  the  trees  and  their  ability  to  produce  larger  yields. 
Many  orchards  do  not  show  any  such  ability  to  produce  large  crops, 
but  such  a  failure  must  be  attributed  to  lack  of  pruning  and  care, 


THE   ALMOND   IN    CALIFORNIA  15 

rather  than  to  any  inherent  inability  of  the  large  trees  to  produce 
nuts.  Again,  trees  on  the  rich  and  moist  bottom  lands  may  be  kept 
so  vigorous  and  healthy  by  good  care  that  they  are  apparently  able 
to  endure  lower  temperatures  than  less  vigorous  trees  on  the  shallow 
and  poor  upland  soils  where  frosts  are  less  common  or  severe. 

Many  recent  plantings  have  been  made  along  the  lower  foothills 
on  the  west  side  of  the  Sacramento  "Valley.  The  three  most  important 
districts  where  these  plantings  have  been  made  are  west  of  Dunnigan, 
Arbuckle  and  Corning.  The  plantings  in  these  districts  are  mostly 
on  a  gravelly  clay  or  clay  loam  soil  which  is  not  as  rich  nor  generally 
as  deep  as  the  bottom  lands  and,  consequently,  the  trees  are  some- 
what smaller,  but  they  have  the  advantage  of  freedom  from  spring 
frosts  due  to  superior  air  drainage.  The  problem  in  this  district  is 
chiefly  one  of  moisture  retention  by  cultivation,  as  in  most  cases  the 
growers  are  unable  to  get  water  for  irrigation  at  a  reasonable  cost, 
if  at  all. 

The  valley  districts  extend  to  Tehama  County  and  down  the  east 
side  of  the  Sacramento  River,  the  same  as  on  the  west  side,  the  prin- 
cipal centers  being  at  Chico,  Durham,  Liveoak,  Pennington  and  Sut- 
ter. Parts  of  the  Liveoak  section  are  too  low  and  many  orchards 
have  suffered  from  poor  drainage  both  of  water  and  air. 

The  foohill  sections  on  the  east  side  are  principally  around 
Antelope,  Fairoaks  and  Orangcvale  in  Sacramento  County  and  the 
southern  end  of  Placer  County.  Here  the  danger  from  frost  is 
slightly  greater  than  on  the  western  foothills  because  of  the  proximity 
to  the  snow-covered  Sierra  Nevada  Mountains.  On  the  other  hand, 
water  from  the  Sierras  renders  irrigation  possible  at  a  reasonable  cost, 
so  the  trees  can  be  kept  in  good  condition.  Care  must  be  exercised 
here  to  avoid  frost  pockets.  There  is  also  danger  of  poor  soil  drainage 
in  the  swales. 

SAN  JOAQUIN  VALLEY  AND  FOOTHILL  SECTIONS 
Conditions  here  blend  very  much  into  those  of  the  Sacramento 
Valley  sections.  Continuing  south  there  are  plantings  around  Acampo, 
Lodi,  Stockton,  Linden,  Ripon,  Modesto  and  more  scattered  plantings 
farther  up  the  valley.  The  clanger  from  spring  frosts  increases  south- 
ward due  to  the  earlier  blooming  of  the  trees.  In  some  of  these 
sections,  notably  around  Ripon  and  Modesto,  the  excessive  use  of 
irrigation  water  for  alfalfa  and  other  crops  has  resulted  in  a  rise  of 
the  water  table  in  many  places  until  it  is  within  a  foot  or  two  of  the 
surface  during  the  summer  months,  and  in  many  other  places  comes 
to  within  four  feet  of  the  surface. 


16 


UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 


On  the  west  side  of  the  San  Juaquin  Valley  the  principal  plantings 
have  been  in  eastern  Contra  Costa  County.  Most  of  these  orchards 
are  of  old  trees,  planted  from  15  to  30  years  ago.  In  order  to  obtain 
satisfactory  air  and  soil  drainage  the  orchards  were  planted  on  the 
rolling  hills,  the  soil  being  nearly  all  blow-sand.  Irrigation  is  too 
expensive  to  be  installed  on  most  of  this  land,  and  the  problem  in  that 
section  is  to  conserve  moisture  and  at  the  same  time  hold  the  soil  in 
place  and  prevent  it  from  being  carried  away  by  the  wind. 


Fig.  3. — Typical  hillside  orchard  of  Jordan  almonds  near  Los  Gatos.  Trees 
are  variable  in  size,  and  some  are  missing.  In  the  right  foreground  is  a  typical 
spot  of  missing  trees  resulting  from  Oak  fungus  infection. 


THE  COAST  SECTION 

Almonds  were  planted  quite  extensively  in  past  years  in  many 
of  the  coast  valleys,  such  as  the  Santa  Clara,  and  where  they  were 
protected  from  the  direct  influence  of  the  moist  ocean  breezes,  they 
apparently  did  well.  Later  most  of  these  orchards  were  replaced  by 
prunes  and  apricots  as  they  were  generally  found  to  be  better  paying 
crops  in  these  valleys.  On  the  hills,  however,  many  typical  hillside 
orchards  remain,  as  shown  in  figure  3. 

Localities  directly  affected  by  the  coast  breezes  have  proved  them- 
selves to  be  unfit  for  commercial  almond  culture. 


THL   ALMOND    IN    CALIFORNIA  17 

INTERIOR  COAST  VALLEYS   AND  HILLS 

Back  from  the  coast  In  the  smaller  valleys  and  on  the  hills  where 
the  coast  fogs  seldom  reach,  many  locations  may  be  found  where 
almonds  are  producing  successfully.  These  favorable  localities  are 
scattered,  owing  to  lack  of  proper  soil  or  moisture  conditions. 

Paso  Robles  District. — The  one  outstanding  district  in  the  coast 
hills  where  the  almond  is  being  grown  successfully  is  in  the  country 
west  of  Paso  Robles.  There,  at  an  elevation  ranging  from  900  to  2000 
feet,  where  there  is  sufficient  air  drainage  to  the  considerably  lower 
land  near  by,  the  almonds  are  doing  well.  These  plantings  are,  in 
most  cases,  on  a  comparatively  heavy  soil,  sometimes  approaching 
adobe,  and  underlaid  by  marl.  This  limestone  formation  is  q^ite 
permeable  to  both  water  and  the  roots  of  the  trees,  and  the  rock  itself 
acts  as  a  sponge  and  holds  considerable  quantities  of  moisture.  On  the 
other  hand,  consisting  of  steep  hills,  the  land  is  excellently  drained 
and  the  trees  seldom  suffer  from  standing  water  around  the  roots. 

The  chief  objection  is  that  most  of  this  land  is  very  shallow,  gen- 
erally ranging  from  two  to  four  or  five  feet  deep.  In  some  places 
almonds  are  found  growing  where  the  marl  is  so  close  to  the  surface 
as  to  be  turned  up  by  the  plow.  This  makes  the  retention  of  moisture 
for  the  use  of  the  trees  a  serious  problem.  The  trees  do  not  attain 
large  size  on  such  soils  and  the  nuts  are  inclined  to  be  somewhat 
smaller  than  normal.  The  steep  character  of  much  of  the  land  makes 
tillage  and  spraying  rather  difficult  and  expensive.  As  long  as  the 
price  of  the  land  is  kept  down  to  a  reasonable  figure,  the  grower  can 
afford  to  put  more  money  into  the  care  of  both  land  and  trees.  It 
must  be  thoroughly  understood  that  there  are  many  localities  close  to 
Paso  Robles  that  are  greatly  subject  to  frost  and  hence  not  at  all 
suited  to  almond  culture.  This  is  especially  true  of  the  lands  directly 
around  and  east  of  Paso  Robles,  and  also  of  any  of  the  comparatively 
low  lands  throughout  the  district. 

SOUTHERN   CALIFORNIA 

The  entire  coast  district  of  Southern  California  has  practically 
proved  itself  to  be  unfitted  for  almond  culture,  except  at  elevations 
above  1500  or  2000  feet.  The  limiting  factor  seems  to  be  the  lack 
of  a  sufficiently  definite  winter  season  at  the  lower  elevations.  Trees 
are  inclined  to  bloom  too  early  in  the  season  or  before  the  winter  is 
over. 

Above  1500  or  2000  feet  the  increased  elevation  gives  a  sufficiently 
definite  cold  winter  season  and  the  trees  tend  to  blossom  at  more 


18  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

seasonable  times.  Aside  from  scattered  plantings  in  the  hills  of  San 
Diego  County  and  a  few  orchards  around  Hemet  and  San  Jacinto  in 
Riverside  County,  the  principal  plantings  are  at  Banning  and  in  the 
Mojave  Desert. 

Banning  District. — Within  a  radius  of  three  miles  of  Banning, 
with  an  average  elevation  of  2300  feet,  where  a  plentiful  supply  of 
water  is  to  be  had  from  the  mountains  to  the  north,  are  a  large  number 
of  orchards  ranging  in  age  from  2  to  29  years.  The  bulk  of  the 
plantings  were  made  during  1910  and  1911.  This  is  the  oldest  district 
in  southern  California  and  has  proved  itself  to  be  well  fitted  for 
almond  culture. 

Antelope  Valley  and  Vicinity. — The  old  plantings  in  the  Mojave 
Desert  are. few  and  far  between.  They  have,  however,  served  as  an 
impetus  for  large  plantings  in  recent  years  many  of  which  have 
turned  out  to  be  failures.  This  happened  in  many  portions  of  Ante- 
lope Valley,  west  of  Lancaster,  on  the  Southern  Pacific  Railroad  in 
northern  Los  Angeles  County.  Many  more  of  these  plantings  are 
young  and  still  have  to  prove  themselves. 

Orchard  almond  trees  are  never  grown  from  seed,  as  they  do  not 
reproduce  true  to  type,  but  are  propagated  by  budding  desirable 
varieties  on  seedling  roots  in  the  manner  commonly  employed  in 
nursery  practices  for  other  stone  fruits,  like  the  peach.  Every  grower 
must  decide,  however,  on  what  rootstocks  he  will  plant  his  trees. 

EOOTSTOCKS 

There  is  much  to  learn  yet  regarding  the  behavior  of  the  different 
roots  under  varying  conditions  when  used  as  stock  for  the  almond, 
but  sufficient  information  has  already  been  gathered  to  permit  of 
certain  recommendations  being  made. 

Almond  Boot.- — The  greatest  proportion  of  almonds  in  this  state 
are  on  almond  roots.  Where  the  most  desirable  soil,  moisture  and 
drainage  conditions  exist  it  is  best  to  select  the  almond  root.  It  will 
live  in  comparatively  dry  soils,  but  cannot  be  expected  to  make  a  tree 
of  large  size  or  bear  crops  of  nuts  if  the  dry  conditions  continue. 
Where  irrigation  is  not  available,  and  the  soil  is  deep  and  of  proper 
texture,  sufficient  moisture  may  be  retained  in  most  years  by  cultiva- 
tion to  enable  the  tree  to  grow  and  bear  fruit.  When  extra  dry  years 
come,  the  almond  root  may  not  enable  the  tree  to  grow  or  produce 
any  better  than  would  another  kind  of  root,  but  it  will  carry  the  tree 
over  a  few  dry  seasons  as  well  or  better  than  any  other.  Then,  when 
sufficient  moisture  does  come,  the  almond  root  is  ready  to  start  the 
tree  off  in  its  normal  course  with  the  least  loss  of  time. 


THE   ALMOND   IN   CALIFORNIA 


19 


The  bitter  almond  is  often  recommended  as  being  superior  to  the 
sweet  almond  as  a  stock.  This  claim  has  never  been  proved.  Experi- 
ments indicate  that  there  is  fully  as  much  variation  between  the  bitter 
almond  seedlings  grown  from  seed  from  different  trees  as  there  is 


Fig.  4. — Languedoc  almond  on  peach*  root ;  typical  of  other  trees  in  same 
orchard,  near  Davis.  Planted  about  forty-seven  years  before.  Compare  with 
trees  in  same  orchard  on  Myrobalan  root,  as  shown  in  Fig.  5. 

between  seedlings  from  bitter  and  sweet  almonds.  Both  are  equally 
subject  to  attack  by  gophers.  The  grower's  chief  object,  therefore, 
should  be  to  secure  as  healthy,  vigorous  trees  as  possible  whether  they 
be  on  sweet  or  bitter  almond  roots. 


*  As  this  bulletin  goes  to  press  doubt  is  raised  as  to  whether  some  of  these 
trees  may  not  be  on  almond  stock,  but  this  in  no  material  way  affects  the  dis- 
cussion. 


20 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


Peach  Root. — Where  the  soil  moisture  is  quite  variable  in  different 
portions  of  the  soil,  or  variable  from  time  to  time  during  the  growing 
season,  the  peach  root  will  probably  be  most  satisfactory.  Soils  less 
than  six  or  eight  feet  deep,  or  where  gravelly  or  hardpan  layers  occur 
at  less  depths,  are  not  satisfactor}'  in  most  cases  for  the  almond  root, 
and  under  these  conditions  the  peach  root  is  better.  The  peach  root  is 
a  little  better  where  irrigation  is  practiced  during  the  summer,  and 
especially  so  where  there  is  danger  of  slow  drainage  of  excess  water 
from  the  soil.    The  peach  does  not  thrive  with  standing  water  around 


Fig.  5. — Languedoc  almond  on  Myrobalan  root,  typical  of  many  other  trees 
in  same  orchard,  near  Davis,  planted  about  forty-seven  years  ago.  Compare  with 
trees  planted  same  time  on  peach  root  as  shown  in  Fig.  4. 


its  roots,  but  will  better  withstand  fluctuating  or  temporary  extremes 
in  water  supply  than  the  almond.  Its  union  with  the  almond  is 
entirely  satisfactory.    See  figure  4. 

Davidiana  Root. — Within  the  last  five  or  six  years  the  United 
States  Department  of  Agriculture  has  introduced  the  seed  of  a  Chinese 
peach,  Prunus  davidiana,  the  root  of  which  is  more  resistant  to  alkali 
than  the  ordinary  peach.  This  has  been  found  to  unite  readily  with 
the  almond,  although  experiments  have  not  yet  gone  far  enough  to 
fully  determine  its  true  value.  It  gives  promise,  however,  of  being 
a  very  desirable  stock  for  sections  where  alkali  may  be  troublesome. 


THE   ALMOND    IN    CALIFORNIA  21 

Undesirable  Boots. — The  Myrobalan  plum  lias  frequently  been 
recommended  as  a  stock  for  the  almond  on  poorly  drained  soils.  The 
two  make  a  strong  union,  bul  the  plum  root  grows  much  slower  than 
the  almond  top,  as  indicated  in  figure  5.  A  comparison  with  figure  4, 
in  which  both  trees  are  48-year-old  Languedoc,  shows  that  the  trees 
on  Myrobalan  root  are  pinched-in  below  the  union  while  those  on  peach 
root  are  swollen  at  the  base.  Even  young  trees  siiow  the  same  pinch- 
ing-in  below  the  union.  Almond  trees  on  Myrobalan  root  do  not  make 
as  large  trees  nor  do  they  bear  satisfactory  crops  in  any  portion  of 
the  state  where  it  has  been  possible  to  compare  them  with  the  same 
varieties  on  other  roots  in  similar  situations. 

The  apricot  is  occasionally  recommended  because  of  its  strong, 
thrifty  growth,  but  it  is  a  mistake  to  attempt  to  use  it,  as  the  union 
is  not  satisfactory.  The  trees  grow  thriftily  for  awhile,  but  before 
they  reach  full  bearing  they  either  break  off  at  the  union  or  are 
blown  over  above  the  union  by  moderate  winds. 

TOP-WORKING  OLD  TREES 

Often  through  injudicious  selection  of  varieties  for  original  plant- 
ings, or  for  some  other  reason,  it  becomes  desirable  to  work  over  old 
trees  to  more  desirable  varieties.  This  may  be  done  by  budding  or 
grafting.  In  either  case  the  tree  may  be  entirely  reworked  in  one 
season  or  one-half  may  be  done  the  first  season  and  the  other  half  the 
next.  The  almond  will  recover  fully  if  completely  deheaded  to  a 
height  of  from  five  to  six  feet  from  the  ground,  provided  it  is  not 
subjected  to  severe  winds  or  excessive  moisture  in  the  soil.  "Winds 
are  liable  to  break  off  the  new  top  during  the  first  year  of  two.  Where 
these  are  dangerous  it  may  be  well  to  leave  half  of  the  tree  on  the 
windward  side  to  be  worked  the  second  season.  The  remaining  por- 
tions will  help  to  serve  as  a  windbreak  until  the  top-worked  portion 
of  the  tree  has  a  chance  to  unite  solidly  with  the  stub  of  the  main 
branch  to  which  it  is  attached.  Where  winds  are  not  likely  to  do 
damage  it  is  generally  the  most  economical  method  to  work  over  the 
entire  tree  at  one  time.  If  the  roots  are  subjected  to  excessive 
moisture  conditions  during  the  first  season,  the  new  growth  may  be 
unusually  vigorous  and  much  more  likely  to  be  blown  out  as  a  result 
of  the  heavy  top  and  the  poor  attachment  to  the  stub.  "Sour-sap" 
may  also  be  very  serious.  Under  such  conditions  leaving  half  the 
tree  the  first  season  will  enable  it  to  distribute  the  growth  more  evenly 
with  less  undesirable  forcing. 

Whether  the  top-working  shall  be  done  by  budding  or  grafting 
depends  largely  upon  the  wishes  of  the  grower  and  the  skill  of  the 


22 


UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 


workman.  Grafting  will  give  a  new  tree  more  quickly  than  budding, 
because  by  the  latter  method  a  year  is  lost  in  growing  a  supply  of 
new  wood  on  the  stubs  into  winch  the  buds  must  be  placed.  By  graft- 
ing, the  new  scions  may  start  growing  the  first  spring  without  any 
delay.  Ordinarily  the  best  method  is  to  graft  the  trees  the  first 
winter  and  then,  where  the  grafts  fail  to  grow,  buds  may  be  inserted 
in  the  new  growth  which  will  come  from  the  stub.  During  the  first 
two  seasons  especially,  great  care  must  be  exercised  to  keep  out  the 
sprouts  that  interfere  witli  the  growth  of  the  scions.     At  the  same 


Fig.  (i. — Twenty-seven-year-old  trees  deheaded  two  years  before,  showing  the  break- 
off  of  the  new  growth  by  strong  winds. 


time,  all  water-sprouts  should  not  be  removed  during  the  first  summer 
or  there  will  not  be  sufficient  leaf  surface  to  perform  the  necessary 
functions  of  the  tree.  In  addition,  the  scions  tend  to  grow  so  rankly 
that  they  will  be  top-heavy  and  much  more  liable  to  be  blown  out  by 
the  wind,  as  shown  in  figure  6.  This  may  largely  be  prevented  by 
pinching  the  ends  of  the  new  scion  growth  during  the  early  summer 
to  force  lateral  branching.  At  the  end  of  the  first  year  all  water- 
sprouts  should  be  removed  leaving  nothing  but  the  growth  from  the 
scions. 


THE   ALMOND   IN    CALIFORNIA 


23 


PLANTING 

The  usual  preparation  given  laud  for  orchard  purposes  prior  to 
planting  should  be  applied  to  laud  being  prepared  for  almonds. 
Special  care  must  be  given  to  insure  thorough  aeration  of  the  subsoil 
by  breaking  up  all  hardpan,  plow-pan  or  other  compacted  layers  in 
the  soil,  where  possible. 


Pig.  7. — Almonds  planted  twelve  feet  apart.  Trees  in  very  weak  condition  and 
almost  entirely  defoliated  by  mites  before  harvest.  The  few  nuts  ripening  on  the 
trees  are  small  ' '  sticktights.  "     Photo  taken  September  21,  1915. 

Distance. — Almonds  in  most  soils  should  be  planted  30  X  30  feet 
on  the  square.  In  rich,  deep  soils  the  trees  quickly  fill  the  intervening 
space,  the  roots  occupying  the  entire  soil  area  long  before  the  tops 
touch.  In  poor,  shallow  soils,  or  soils  deficient  in  available  moisture, 
the  trees  may  not  occupy  the  entire  area  above  ground,  but  the  roots 
will  require  more  horizontal  feeding  space  to  enable  them  to  make 
the  size  trees  and  bear  the  crops  that  they  should. 

Trees  planted  too  close  together  often  abstract  the  moisture  from 
the  soil  before  the  growing  season  is  completed.  This  shortage  of 
moisture,  with  the  aid  of  mites,  commonly  called  red-spider,  causes 
the  loss  of  the  leaves  long  before  they  normally  should  drop.     Under 


24  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

such  conditions  the  fruit  buds  are  unable  to  make  the  vigorous  growth 
which  they  should.  These  weak  buds  are  unable  to  endure  the  degree 
of  frost  or  other  unfavorable  conditions  that  stronger  ones  withstand 
without  serious  injury. 

The  trees  must  have  plenty  of  sunlight  and  air.  If  planted  too 
close,  the  trees  tend  to  grow  too  high,  each  one  striving  for  the  light 
which  is  only  available  from  above.  In  figure  7  the  upward  tendency 
of  the  trees  is  clearly  shown.  Such  trees,  if  pruned  as  they  ought  to 
be,  have  a  much  greater  tendency  to  send  out  numerous  water-sprouts 
than  trees  which  have  plenty  of  room  for  the  tops  to  expand  laterally. 
After  the  tops  of  the  trees  interlock  and  shut  out  the  sunlight  from 
the  lower  portions,  the  smaller  branches  and  fruit  spurs  in  those  parts 
gradually  weaken  and  die,  and  eventually  the  entire  crop  is  produced 
on  or  near  the  tops  of  the  trees,  where  direct  sunlight  is  available,  as 
shown  in  figure  7.  The  excessive  upward  growth  of  the  trees,  with 
the  consequent  forcing  of  the  fruit  bearing  to  the  top,  not  only  greatly 
increases  the  difficulty  and  cost  of  pruning,  spraying  and  harvesting, 
but  reduces  the  possible  bearing  surface  of  the  trees. 

Setting  the  Trees. — The  utmost  care  is  necessary  in  setting  out  the 
trees  to  secure  a  uniform  stand  of  vigorous  trees.  The  trees  are 
planted  much  the  same  as  other  deciduous  orchard  trees,  but  care 
must  be  used  to  spread  the  roots  well  to  secure  a  thorough  compacting 
of  the  soil  around  all  the  roots,  and  to  see  that  the  trees  are  not  planted 
deeper  than  they  were  in  the  nursery. 

CULTURE 

Soil  Handling. — The  almond  is  one  of  the  most  exacting  of  fruits 
as  regards  its  cultivation.  The  assumption  is  very  often  made  by 
growers  that  because  the  tree  will  live  through  periods  of  prolonged 
drouth,  it  will  also  thrive  under  careless  or  poor  methods  of  cultiva- 
tion. That  this  is  entirely  erroneous  may  be  inferred  from  the  fact 
previously  referred  to  that  the  almond  draws  more  heavily  upon  the 
plant  food  of  the  soil  for  the  ripening  of  its  crop  than  any  of  the 
common  orchard  fruits.  Experience  has  abundantly  proved  that 
many  almond  orchards  are  not  bearing  profitable  crops  because  the 
requisite  soil  constituents  are  not  available  in  sufficient  quantities 
during  the  long  growing  season.  The  reasons  for  this  condition  may 
be  one  or  several.  First,  there  may  not  be  sufficient  moisture  avail- 
able throughout  the  season,  or  it  may  not  be  distributed  evenly  or  in 
sufficient  amounts  throughout  the  entire  soil  area.  Second,  there  may 
be  insufficient  aeration  of  the  soil;  and  third,  there  may  not  be  suf- 


THK   ALMOND   IN   CALIFORNIA  25 

ficient  humus  to  fix  the  soluble  plant  food  in  the  soil  and  render  it 
readily  available  as  needed  by  the  roots. 

Proper  distribution  of  moisture  in  sufficient  quantities  is  essential 
to  secure  adequate  solution  of  the  mineral  elements  needed  by  the 
roots  for  the  use  of  the  tree  in  all  its  parts.  Sufficient  aeration  is 
needed  to  provide  for  the  normal  oxidation  and  weathering  of  the  soil 
particles,  and  also  for  the  respiration  of  the  roots  themselves. 

There  seems  to  be  no  question  about  the  value  of  spring  plowing 
and  cultivation  to  put  the  soil  in  good  physical  condition,  but  many 
growers  apparently  question  the  value  of  summer  cultivation.  Though 
the  surface  of  the  soil  appears  to  be  unchanged  after  a  period  of 
several  months,  the  fact  is  entirely  overlooked  that  the  structure  of 
the  mulch  has  been  gradually  changed  and  capillarity  to  the  surface 
has  been  restored.  The  result  is  that  evaporation  takes  places  so 
rapidly  from  soils  in  such  a  condition,  as  well  as  from  the  leaves  of 
the  trees,  that  long  before  the  end  of  the  season  the  moisture  is  prac- 
tically gone. 

The  methods  and  tools  used  are  much  the  same  as  for  other  orchard 
trees  and  it  is  only  necessary  to  call  attention  to  items  likely  to  be 
neglected.  Spring  plowing  should  vary  in  depth  from  year  to  year 
to  avoid  the  formation  of  an  impervious  plow-sole.  The  depth  to 
plow  ranges  from  a  minimum  of  six  inches  to  ten  or  twelve  inches  or 
more  as  desirable.  Summer  cultivation  should  be  kept  up  at  least 
once  a  month,  and  preferably  oftener,  throughout  the  summer  months 
and  the  soil  should  be  stirred  to  a  depth  of  four  inches  to  provide  a 
mulch  sufficient  to  hold  the  moisture  effectively  in  the  hot,  dry  climates 
where  almonds  are  grown.  The  actual  number  of  cultivations  neces- 
sary will  depend  on  the  types  of  soil.  Harness  with  projecting  hames 
or  broad  singletrees  or  with  projections  of  any  kind  to  catch  on  the 
branches  or  bark  of  the  trees  should  never  be  used  in  an  orchard. 

Cover  Crops. — Constant  cultivation  throughout  the  summer  allows 
the  humus  to  be  burned  out  of  the  surface  soil  and,  by  hindering  the 
growth  of  vegetation,  prevents  the  addition  of  a  natural  supply  of 
humus  to  replace  that  which  has  been  lost.  It  is  necessary,  therefore, 
that  some  artificial  means  be  used  to  supply  the  deficiency.  The 
annual  growth  of  winter  cover  crops  to  be  plowed  in  during  the 
spring,  while  not  entirely  replacing  the  humus  burned  out  in  the 
summer,  serves  to  reduce  the  annual  loss  and  at  the  same  time  assists 
materially  in  improving  the  texture  of  the  soil. 

A  shade  crop,  such  as  alfalfa,  may  be  grown  successfully  in  mature 
orchards  where  irrigation  water  is  available,  and  where  perfect  drain- 


26  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

age  of  surface  and  subsoil  can  be  maintained.  During  the  first  four 
or  five  years  or  more  such  a  crop  is  generally  a  detriment  to  the 
almond  trees,  but  after  the  trees  reach  maturity  it  may  be  beneficial 
in  securing  better  drainage  and  areration  of  the  soil  by  the  penetra- 
tion of  the  numerous  roots  to  considerable  depths  and  their  consequent 
decay  when  it  is  plowed  in.  Alfalfa  also  supplies  nitrogen  to  the  soil 
and  thus  gradually  increases  the  fertility.  The  great  danger  with 
such  a  crop  is  that  the  orchardist  is  apt  to  irrigate  for  the  alfalfa  at 
the  expense  of  the  trees  because  of  the  quicker  returns  from  the 
former.  In  deep,  rich  soils  the  cuttings  of  alfalfa  may  be  removed 
from  the  land,  though  the  last  cutting  in  the  fall  should  be  allowed  to 
remain  on  the  land.  Where  this  is  done,  a  natural  mulch  is  obtained 
which  helps  to  increase  the  supply  of  humus.  If  the  soil  is  poor  and 
lacking  in  humus  it  is  better  to  leave  more  cuttings  of  the  alfalfa  on 
the  ground  to  decay.  As  this  continues  the  soil  becomes,  through  the 
increased  accumulations  of  humus,  more  permeable  and  yet  more 
retentive  of  moisture,  and  less  irrigation  will  serve  the  trees  more 
effectively. 

During  the  early  spring  a  well-established  stand  of  alfalfa  may 
assist  so  materially  in  getting  rid  of  the  excess  water  in  the  soil  that 
sour-sap,  fruit  drop  and  kindred  ills  resulting  from  the  unseasonable 
warm  weather  while  the  ground  is  filled  with  water  and  the  trees  are 
starting  into  growth,  may  be  greatty  reduced  or  avoided  entirely. 

Irrigation. — Water  for  irrigating  almonds  must  always  be  used 
with  great  care  whether  it  be  in  summer  or  winter.  All  water  should 
be  so  applied  that  it  will  readily  spread  through  the  soil  and  not 
remain  in  excessive  quantities  for  any  length  of  time.  Water  should 
not  be  applied  during  blossoming  or  setting  of  the  fruit  in  the  spring 
or  within  a  week  or  more  of  harvest.  On  the  other  hand,  water  applied 
just  before  the  hulls  commence  to  open,  where  the  soil  has  become  too 
dry,  greatly  reduces  the  number  of  sticktights,  or  almonds  in  which 
the  hulls  stick  to  the  ripening  nuts  without  opening. 

Fertilization. — Little  or  no  systematic  work  has  been  done  up  to 
the  present  time  in  the  use  of  commercial  fertilizers  on  almonds.  The 
use  of  barnyard  manure  is  desirable  wherever  obtainable.  The  value 
of  almond  hulls  as  fertilizers  is  doubtful  because  of  the  difficulty  of 
bringing  about  their  thorough  decay  when  applied  in  sufficient  quan- 
tities to  be  worth  while.  The  use  of  lime  to  correct  soil  acidity  and 
for  improving  the  texture  of  heavy  soils  will  be  found  desirable  where 
this  is  obtainable  at  reasonable  rates. 


THK    ALMOND    IN    CALIFORNIA 


27 


PRUNING 

The  almond  trees  normally  set  a  larger  number  of  fruit  buds  than 
they  are  capable  of  maturing.  The  number  of  blossoms  set  on  a 
healthy  tree  to  produce  a  full  crop  will  be  generally  not  more  than 
20  per  cent  of  the  total  number  which  opened  in  the  spring,  and  often- 
times much  less.  It  has  frequently  been  noted  that  trees  which  are 
somewhat  lacking  in  vigor  are  inclined  to  set  a  larger  number  of  fruit 
buds  than  those  that   arc  strong  and  vigorous.      The  normal  set  of 


Fig.  8. — Typical  Drake  almond  tree  in  University  Farm  orchard ; 
nine  years  old. 

blossoms  on  a  young,  vigorous  tree  is  shown  in  figure  2.  The  result 
is  that  with  the  sub-normal  strength  of  such  trees  being  distributed 
among  the  extra  number  of  fruit  buds,  the  latter  are  not  able  to 
develop  into  the  strong,  healthy  buds  they  should.  The  results  of 
such  conditions  have  been  discussed  on  pages  23,  bottom,  and  24,  top. 
One  of  the  best  means  of  securing  and  keeping  healthy,  productive 
trees  is  by  careful,  thoughtful  and  systematic  pruning.  The  treat- 
ment given  most  of  the  almond  orchards  would  indicate  that  the 
growers  consider  pruning  to  be  one  of  the  least  important  of  the 
cultural  practices. 

To   be   most   effective,    pruning   must  be   followed    sj'stematically 
throughout  the  entire  life  of  the  tree.     The  details  of  the  practice  will 


28 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


vary  greatly,  depending  on  the  soil,  moisture  and  climatic  conditions 
surrounding  the  tree,  as  well  as  other  treatment  accorded  it.  At 
planting  time,  it  is  generally  agreed  that  the  tree  should  be  cut  back 
to  between  18  and  24  inches  from  the  ground  to  reduce  the  top  to 


Fig.  9. — Typical  Languedoe  almond  tree  in  University  Farm  orchard ; 
nine  years  old. 


correspond  to  the  shortened  root  system  and  to  form  a  low  head  for 
the  tree.  A  low  head  is  desirable  to  avoid  sunburn  of  the  trunk  and 
to  keep  the  tree  within  easy  reach  for  pruning,  spraying  and  harvest- 
ing. During  the  first  summer  in  the  orchard  much  can  be  clone  to 
obtain  a  well-balanced  head,  to  get  the  main  branches  well  spaced  on 
the  trunk,  and  to  prevent  crowding  later  on,  by  pinching  out  all 


THE   ALMOND   IN   CALIFORNIA 


29 


undesirable  growth  as  fast  as  it  appears  and  forcing  the  growth  into 
those  parts  of  the  tree  which  are  to  remain.  If  these  branches  tend 
to  grow  too  long  and  willowy,  they  may  be  made  to  branch  by  pinch- 
ing back  when  they  attain  the  desired  height.     In  this  way,  if  the  tree 


Fig.  10. — Typical  Nonpareil  almond  tree  in  University  Farm  orchard;  nine  years 
old.     Note  numerous  watersprouts  which  must  be  removed. 


can  be  kept  growing  vigorously,  the  beginning  of  an  excellent  founda- 
tion framework  may  be  developed  the  first  year. 

The  following  winter,  when  the  tree  is  one  year  old  in  the  orchard, 
if  it  has  grown  too  vigorously  and  the  branches  are  too  long  and 
willowy  and  not  properly  branched  it  should  be  headed  back  to  im- 
prove the  shape  and  symmetry  of  the  whole  tree.  If  the  tree  has  not 
made  sufficient  growth  to  give  it  a  properly  shaped  head,  it  should 
also  be  cut  back  even  more  severely  than  in  the  case  of  the  too  vigorous 


30 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


growth.  There  sometimes  will  be  trees  that  during  the  first  year  will 
develop  such  a  well-shaped  and  stocky  frame  that  no  further  heading 
will  be  necessary,  all  future  pruning  being  limited  to  thinning  out 
undesirable  and  interfering  branches.  Ordinarily,  however,  it  will  be 
highly  desirable  or  necessary  to  continue  the  practice  of  heading-in 


:      :  m 


f&l&ftr*rJ~fc  +mt 


Fig.  11. — Typical  I.X.L.  almond  tree  in  University  Farm  orchard; 
nine  years  old. 


the  yearling  tree  at  least.  As  long  as  heading  continues  it  will  pay 
to  give  special  attention  to  pinching  and  thinning  the  following  sum- 
mer. In  this  way  the  frame  of  the  tree  may  be  developed  more  quickly 
and  the  future  necessity  of  heading  be  materially  lessened.  In  rich 
bottom  lands  where  moisture  is  plentiful,  heading  may  be  necessary 
when  the  tree  is  two,  three  and,  in  extreme  cases.  4  years  old,  in  order 
to  spread  the  tree  and  prevent  it  from  growing  too  high.     The  neces- 


THE    ALMOND    IN    CALIFORNIA 


31 


sity  for  this  can  only  be  determined  by  a  careful  study  of  the  tree 
itself  and  the  conditions  surrounding  it. 


* 


Fig.  12. — Typical  Ne  Plus  Ultra  almond  tree  in  University  Farm  orchard; 

nine  years  old. 


The  habit  of  growth  of  a  given  variety  will  have  a  great  deal  to 
do  with  the  number  of  seasons  during  which  heading  back  will  be 
practiced.  Spreading  varieties,  such  as  the  Drake  (see  figure  8),  if 
making  a  strong,  vigorous  growth,  should  not  be  headed  any  longer 
than  is  necessary  to  start  a  sufficient  number  of  main  branches.    Every 


32  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

opportunity  must  be  given  the  trees  of  this  variety  to  grow  as  upright 
as  possible.  Summer  pruning  of  the  drooping,  undesirable  branches 
wherever  they  develop,  will  help  to  increase  the  growth  of  the  upright 
branches.  By  pruning  as  far  as  possible  to  inside  buds,  every  oppor- 
tunity will  be  given  the  trees  to  grow  upward.  If  trees  of  such 
varieties  make  a  poor,  weak  growth,  a  very  heavy  heading  will  force 
them  to  make  a  stronger  and  more  vigorous  growth  the  following 
season,  provided  any  unfavorable  soil  and  moisture  conditions  are 
corrected.  Care  must  be  exercised  with  these  trees  to  prevent  the 
downward  growth  of  any  of  the  branches  by  pruning  them  off  during 
the  summer,  as  suggested  above.  As  soon  as  a  strong,  upright  growth 
is  started,  no  further  heading  should  be  done,  but  careful  thinning 
by  removal  of  undesirable  growth  should  be  continued. 

Upright  varieties,  such  as  the  Languedoc  (see  figure  9)  and  Texas, 
may  require  heading  for  a  longer  time  than  the  more  spreading  varie- 
ties. It  is  necessary  to  force  them  to  branch  nearer  the  ground  and 
they  should  be  made  to  spread  as  much  as  possible.  Pruning  to  out- 
side buds  and  summer  pinching  will  aid  materially  and  make  it 
unnecessary  to  head  back  after  the  first  two  or  three  years.  Where 
this  is  not  done,  heading  may  be  necessary  at  the  end  of  the  third  and 
possibly  to  the  fourth  year  if  the  tree  is  in  rich,  deep,  moist  soil. 
Another  advantage  of  summer  pinching  and  removal  of  water  sprouts 
is  that  the  trees  are  not  allowed  to  develop  a  thick  "crow's  nest"  at 
the  end  of  the  stubs  where  heading  back  was  done  the  previous  winter, 
making  the  following  winter  pruning  much  easier.  The  habit  of 
growth  of  each  of  the  principal  commercial  varieties  is  shown  in 
figures  8  to  12,  inclusive. 

After  the  main  framework  is  properly  started,  further  pruning 
will  be  limited  to  thinning  out  the  tree  to  keep  it  sufficiently  open  and 
to  remove  all  dead,  injured  and  interfering  branches.  Most  of  the 
growth  after  this  will  continue  from  the  ends  of  the  remaining 
branches  and  as  the  trees  grow  higher  they  will  tend  to  branch  more. 
All  cross  branches  and  those  that  are  liable  to  interfere  later  should 
be  taken  out.  All  water  sprouts  should  be  removed  unless  they  are 
needed  to  fill  in  undesirable  open  spaces. 

As  the  trees  come  into  full  bearing  and  approach  maturity,  the 
vigorous  wood  growth  will  cease  and  will  be  replaced  by  a  moderate 
yearly  growth  of  wood  which  will  gradually  increase  the  size  of  the 
tree  without  making  it  unmanageable.  Where  trees  continue  to  make 
excessive  wood  growth  when  they  should  be  bearing,  the  trouble  may 
generally  be  traced  to  unusually  rich,  moist  soil,  a  condition  which 


TIIF,    ALMOND    IN    CALIFORNIA  33 

pruning-  cannot  correct.  It  may  be  beneficial  to  stop  pruning 
altogether  for  a  few  years,  which  will  be  Likely  to  throw  the  trees 
into  heavy  bearing  and  thus  stop  excessive  wood  growth.     After  the 


Fig.  13. — Eighteen-year-old  almond  trees  deheaded  six  feet  from  ground,  in 
the  Armstrong  orchard  near  Davis.  Stubs  painted  with  white  lead.  Photo  taken 
February,  1914.     Compare  with  Figs.  14  to  19. 


Fig.  14. — Same  trees  as  Fig.  13,  showing  growth  one  year  after  deheading. 
Photo  taken  March,  1915.  On  some  of  the  trees  long  stubs  were  left  near  the 
bottom  of  the  trees  from  which  new  growth  never  started.  Only  a  moderate 
thinning  out  of  the  new  growth  was  done. 


bearing  habit  is  once  thoroughly  established,  moderate  pruning  may 
be  done  to  get  the  tree  back  into  proper  shape. 

The  mature  tree  should  have  its  branches  so  spaced  that  sunlight 
may  penetrate  to  all  portions  of  the  tree.     This  is  necessary  for  the 


34  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

continued  health  and  life  of  the  fruit  spurs  in  the  lower  portions  of 
the  tree.  If  the  top  is  too  dense,  the  new  growth  can  only  continue 
in  the  top  and  outer  portions  of  the  tree  where  sunlight  can  penetrate. 
When  an  adventitious  bud  does  start  in  the  center  of  the  tree  it 
immediately  makes  a  strong  vigorous  growth  to  reach  the  sunlight  far 
above.  Such  a  growth  is  called  a  water  sprout.  If  the  trees  are  kept 
so  pruned  that  the  shadow  on  the  ground  during  the  greater  part 
of  the  day  is  mottled  with  sunlight  while  the  trees  are  in  full  leaf, 


Tig.  15. — Same  trees  as  Fig.  14,  showing  two  seasons'  growth  after  deheading. 
Photo  taken  February,  1916,  just  after  pruning  had  been  completed. 

the  small  growth  may  be  maintained  in  the  center  and  the  bearing 
surface  greatly  increased.  Where  this  is  done  the  trees  will  not  tend 
to  grow  as  high  as  they  otherwise  would.  Pruning  of  healthy,  mature 
trees,  therefore,  will  be  limited  to  thinning  out  and  removal  of  dead 
and  interfering  branches  and  water  sprouts.  Portions  which  grow  too 
high  may  be  brought  down  by  removal  close  to  a  shorter  and  lower 
branch.  By  giving  this  treatment  only  to  small  portions  of  the  tree 
during  a  season,  the  forcing  of  water  sprouts  may  be  largely  avoided. 
Old  trees,  or  those  which,  through  improper  care  or  neglect  have 
become  weak  and  unfruitful,  may  often  be  rejuvenated.  One  method 
is  to  dehead  them  to  a  height  of  about  six  feet  from  the  ground  and 


THE   ALMOND   IN    CALIFORNIA 


35 


to  grow  entirely  new  tops.  By  this  method  about  three  years  are 
required  to  bring  the  trees  back  to  the  point  where  they  are  again 
ready  to  bear  profitable  crops.  The  objections  to  this  are  that  it  is  an 
expensive  operation,  no  crops  whatever  can  be  obtained  for  two  years, 
organisms  of  decay  may  gain  entrance  to  the  wood,  and  sometimes  the 
sodden  shock  to  the  tree  renders  it  more  subject  to  physiological  dis- 
turbances. The  advantages  are  that  if  proper  care  is  given  the  trees 
during   the    rebuilding    period,    much    better    formed    trees    may    be 


Fig.  16. — Same  trees  as  Fig.  14,  showing  three  seasons'  growth  after  dehead- 
ing.  Photo  taken  January,  1917.  No  pruning  done  this  winter.  Trees  have  not 
borne  more  than  a  few  almonds  but  have  a  good  set  of  fruit  buds. 


obtained  and  a  finer  quality  of  bearing  wood  be  secured  throughout 
the  new  trees. 

To  be  successful,  the  deheading  process  must  be  followed  by  careful 
thinning  of  the  sprouts  that  will  be  forced  from  the  old  stubs.  If 
too  much  thinning  is  done  the  first  year,  there  is  danger  of  those  that 
are  left  becoming  top-heavy  and  breaking  off.  This  is  especially 
troublesome  in  sections  subject  to  strong  winds.  The  new  sprouts 
should  be  left  sufficiently  thick  to  help  support  each  other,  and  yet 
should  be  thinned  out  sufficiently  to  prevent  crowding.  At  the  end 
of  the  first  season's  growth,  further  trimming  should  be  done,  giving 
those  branches  best  adapted  for  the  frame  of  the  new  tree  a  chance 


36  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

to  take  the  lead  the  following  season.  A  sufficient  amount  of  sec- 
ondary growth  should  be  left  to  help  take  care  of  the  excessive  sap 
flow  in  the  shortened  tree,  but  this  must  be  watched  to  see  that  it  does 
not  interfere  with  the  growth  which  is  to  be  permanent.  By  the  end 
of  the  second  year,  the  permanent  branches  should  be  sufficiently 
strong  and  firm  to  permit  the  entire  removal  of  all  other  branches. 
The  amount  of  wood  to  be  left  until  the  end  of  the  second  season  and 
then  removed  is  clearly  shown  in  figures  18  and  19.  The  third  year 
the  tree  should  make  sufficient  growth  to   restore  very  largely  the 


Fig.  17. — Same  trees  as  Fig.  14,  showing  four  seasons'  growth  after  dehead- 
ing.  Photo  taken  December,  1917,  after  trees  have  borne  their  first  good  crop  of 
nuts.     No  pruning  has  been  done  since  January,  1916. 

equilibrium  between  the  top  and  the  roots  and  also  produce  a  small 
crop.  Figures  13  to  17,  inclusive,  illustrate  the  steps  in  rejuvenating 
an  orchard  by  the  deheading  process  from  the  start  until  the  trees 
are  again  in  commercial  bearing. 

Some  growers  find  it  more  desirable  to  cut  back  only  one-half  of 
each  tree  at  a  time.  The  shock  to  the  tree  is  not  so  great  and  the 
liability  to  sour-sap  correspondingly  less.  The  halves  of  the  tree  left 
standing  act  as  a  wind-break  to  prevent  the  blowing  out  of  the  new 
growth,  which  at  the  same  time  is  less  likely  to  break  off  because  of 
its  slower  and  more  sturdy  growth.     The  objection  to  this  method  is 


THE   ALMOND   IN    CALIFORNIA 


37 


that  the  other  half  must  be  cut  off  the  following  winter  and  the  shap- 
ing process  is  more  or  less  uneven,  and  necessarily  continued  over  a 
long  time. 

The  other  method  of  rejuvenation  is  to  thin  out  gradually  the 
dead  and  weakened  branches  in  the  old  trees  and  rebuild  them  grad- 


Fig.  18. — Two  seasons'  growth  before  pruning  of  almond  trees  deheaded  six 
feet  from  the  ground  January,  1914,  in  the  Armstrong  orchard  near  Davis.  The 
tree  was  only  moderately  thinned  at  the  end  of  the  first  year.  Photo  taken  Feb- 
ruary 2,  1916.  .     .    . 

ually,  removing  only  a  small  portion  in  any  one  year.  As  the  new 
growth  is  forced  ont  it  is  used  to  replace  the  old  wood  where  possible. 
Such  a  system  requires  more  cutting  of  small  branches  high  up  in  the 
tree  to  be  successful,  for  it  must  not  be  opened  to  sunlight  too  sud- 
denly or  sunburn  will  result.  The  cutting  of  a  large  number  of  small 
branches  tends  to  force  the  growth  of  new  buds  over  a  large  propor- 


38 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


tion  of  the  tree  and  if  done  moderately  many  of  these  will  quickly 
develop  into  fruiting  wood.  Eventually,  many  large  branches  may 
have  to  be  removed  as  newer  branches  are  developed,  but  this  must 
necessarily  be  a  comparatively  gradual  process.     The  advantages  of 


Fig.  19. — Same  tree  as  Fig.  18  after  pruning.     The  actual  time  required  to  prune 
this  tree  was  twenty-five  minutes.     Photo  taken  February,  1916. 

this  method  are  that  there  is  no  sudden  shock  to  the  tree,  there  is 
always  sufficient  leaf  surface  to  care  for  any  extra  supply  of  sap 
which  may  be  forced  into  the  tree  by  unfavorable  weather  and  moist- 
ure conditions,  and  cropping  will  be  continuous. 

Whatever  method  of  rejuvenation  is  used,  the  grower  must  be 
very  careful  from  the  first  to  protect  all  large  wounds  by  some  paint 
or  other  protective  covering,  such  as  asphaltum,  to  prevent  checking 
and  weathering  and  to  keep  decay  from  getting  started  and  working 


THE   ALMOND   IN   CALIFORNIA  39 

into  the  heart  of  the  tree.  With  very  large  wounds  a  protective 
covering  must  be  kept  on  during  the  remainder  of  the  life  of  the 
tree,  or  until  the  wounds  heal  over  completely. 

INFLUENCE  OF  CULTUEE  ON  NUTS 

The  effect  of  culture  on  the  nuts  is  quite  marked.  All  varieties 
will  vary  in  size  from  season  to  season  and  in  different  orchards 
during  the  same  season,  depending  on  the  plant  food  and  moisture 
supply  available  during  the  time  the  nuts  are  maturing.  Some 
varieties,  notably  the  Nonpareil,  will  vary  more  in  size  than  in  plump- 
ness, while  other  varieties,  like  the  Ne  Plus  Ultra,  are  more  inclined 
to  produce  somewhat  shriveled  kernels  and  imperfectly  developed 
shells  and  the  variation  in  size  will  not  be  as  great.  As  the  trees 
bear  larger  crops  the  nuts  produced  are  inclined  to  be  smaller.  Young, 
vigorous  trees  with  a  light  crop  will  often  produce  unusually  large 
nuts  with  comparatively  thin  shells.  The  value  of  a  variety,  there- 
fore, will  depend  largely  upon  its  behavior  after  the  trees  reach  full 
maturity  and  bearing. 

OECHAED   HEATING   FOE   FEOST    PEEVENTION 

There  has  been  considerable  interest  in  protecting  almonds  from 
frost  because  of  the  frequency  with  which  they  are  subjected  to  such 
conditions  by  reason  of  their  early  blossoming  habit.  The  use  of 
orchard  heaters  in  some  districts  has  become  a  common  and  successful 
practice.  It  is  possible  to  economically  control  several  degrees  of  frost 
for  three  or  four  nights  or  possibly  more  by  a  judicious  use  of  heaters. 

The  best  type  of  heater  for  almond  orchards  has  not  been 
thoroughly  worked  out  as  yet,  but  the  reservoir  heaters  of  the  Bolton 
or  Hamilton  type  have  been  commonly  and  successfully  used.  The 
former  are  commonly  known  as  ' '  pots. ' '  At  least  75  one  or  two-gallon 
heaters  per  acre  are  necessary  to  control  temperatures  as  low  as  27 
or  28  degrees  F.  Probably  not  over  100  pots  to  an  acre  would  be 
needed  at  most.  Double  the  number  of  pots  should  be  placed  around 
the  outside  row  of  the  orchard  to  afford  the  necessary  protection. 

The  gravity  of  oil  best  suited  for  orchard  heating  is  between  20 
and  25  degrees  Beaume.  It  is  essential  that  it  be  as  free  from  impuri- 
ties, such  as  sulphur,  as  possible.  During  the  spring  of  1917,  orchard 
heating  was  done  very  extensively  in  some  districts  of  the  state  while 
the  trees  were  approaching  full  bloom.  As  the  season  progressed  it 
became  apparent  that  some  serious  injury  had  been  done  by  the 
heating,  for  the  bulk  of  the  blossoms  fell  off  and  the  leaves  turned 


40  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

yellow  iu  streaks  as  if  burned  by  an  acid.  The  appearance  was  exactly 
as  if  the  particles  of  soot  settling'  on  the  pistils  of  the  flowers  and  on 
the  young  leaves  had  absorbed  sulphur  dioxide  gas  (a  product  of  oil 
combustion  where  sulphur  is  contained  in  the  oil)  and  that  the  dews 
uniting  with  it  to  form  sulphurous  acid  had  done  the  damage.  Had 
the  heating  been  done  later  and  only  after  the  trees  had  passed  full 
bloom,  it  is  possible  that  a  much  heavier  set  of  nuts  might  have  been 
secured,  since  the  small  fruits,  where  they  had  formed,  seemed  to  have 
been  uninjured,  only  the  pistils  of  the  flowers  having  been  affected, 
probably  preventing  pollination  and  fertilization  of  the  ovules. 

The  time  of  heating  is  therefore  a  very  important  point.  Almond 
blossoms  become  progressively  more  tender  to  frost  as  they  advance 
in  development.  With  their  petals  on  they  are  not  nearly  as  tender 
as  they  are  after  the  petals  have  fallen.  They  reach  their  most  tender 
stage  after  the  calyx  shucks  have  fallen  from  the  young  expanding 
fruits  before  they  are  the  size  of  a  pea.  Ordinarily,  orchard  heating 
before  the  trees  have  passed  full  bloom  is  a  waste  of  time  and  material 
and  is  often  injurious.  The  most  needed  time  is  for  a  period  of  two 
or  three  weeks  after  the  bulk  of  the  petals  have  fallen,  unless  temper- 
atures below  28  or  29  degrees  are  encountered  before  that  time. 

CROP  HANDLING 

Harvesting. — The  harvesting  of  the  crop  should  be  commenced  as 
soon  as  the  hulls  have  opened  to  their  fullest  extent  and  no  time  should 
be  lost  in  completing  the  work.  The  nuts  in  the  center  of  the  tree  arc 
the  last  ones  to  ripen  and  so  may  be  used  as  indicators.  If  harvesting 
is  commenced  early,  the  nuts  will  cling  to  the  tree  rather  tenaciously 
and  knocking  must  be  very  vigorous  in  order  to  shake  them  loose.  On 
the  other  hand,  if  they  are  allowed  to  hang  too  long  after  ripening, 
a  number  of  difficulties  may  be  encountered.  They  may  be  blown  to 
the  ground  by  light  winds  and  the  cost  of  gathering  be  increased,  as 
quite  commonly  occurs  with  the  Peerless,  or  the  hulls  may  dry  up  and 
in  doing  so,  close  around  the  nuts  to  a  greater  or  less  extent  and  add 
to  the  cost  and  difficulty  of  hulling.  This  is  most  noticeable  with  the 
Nonpareil.  Strong  winds  will  break  off  a  great  many  of  the  nuts  of 
any  of  the  varieties,  and  promptness  is  doubly  essential  where  there  is 
any  likelihood  of  such  winds  during  the  harvest  season.  Depredations 
by  birds  may  cause  serious  losses,  especially  with  the  soft  and  paper- 
shell  varieties.  Infestation  by  worms  may  often  be  quite  serious  in 
the  papershell  varieties  when  they  are  allowed  to  hang  too  long.  In 
case  of  damp  or  foggy  weather  the  shells  turn  dark  and  sometimes 
commence  to  mildew,  requiring  heavier  bleaching  to  brighten  them 


THE   ALMOND   IN   CALIFORNIA 


41 


sufficiently  for  market  demands.     Rain  stains  can  never  be  removed 
entirely  by  bleaching. 

The  crop  is  gathered  by  knocking  the  ripened  nuts  and  hulls  witli 
long  poles  onto  sheets  spread  on  the  ground  under  the  trees.  The 
knocking  should  be  done  near  the  portions  of  the  trees  where  the  nuts 
are  borne  and  by  striking  a  number  of  light,  quick  blows,  rather  than 
by  a  heavy  blow  aimed  to  jar  a  large  branch.     This  will  avoid  injury 


Fig.  20. — Harvesting  almonds  by  knocking  onto  sheets  spread  on  ground. 

to  the  bark  by  bruising  and  will  accomplish  the  work  in  less  time. 
The  blows  should  always  be  delivered  squarely  against  the  branch. 
A  glancing  blow  will  tear  the  bark  and  break  off  a  great  many  fruit 
spurs,  thus  reducing  the  bearing  surface  for  the  next  year.  For  this 
reason  harvesters  must  be  watched  closely  all  the  time  to  insm*e  the 
proper  use  of  the  poles.  The  sheets,  two  in  number,  are  spread  under 
the  trees  so  they  will  overlap  and  catch  all  the  nuts  that  fall  (see 
figure  20).  When  sufficiently  loaded  with  nuts  to  make  dragging  the 
sheets  from  one  tree  to  another  difficult,  they  are  emptied  into  lug 
boxes  and  sent  to  the  huller. 

The  character  of  the  harvesting  equipment  may  vary  considerably, 
depending  on  the  acreage,  character  of  trees  and  ground,  time  re- 


42  UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION 

quired,  capital  available,  and  the  personal  wishes  of  the  owner.  Some 
growers  use  heavy  poles  of  pine,  spruce  or  fir,  while  others  prefer 
the  lighter  bamboo  poles.  The  heavy  poles  are  from  iy2  to  2  inches 
in  diameter  at  the  base  and  from  %  to  1  inch  in  diameter  at  the  top. 
Experience  has  shown  that  poles  of  this  type  over  20  feet  in  length 
become  unweildy,  and  not  only  swing  slowly  but  do  more  damage 
because  of  the  greater  difficulty  of  control.  Most  growers  prefer 
16-foot  poles  with  a  few  20-foot  ones  for  use  in  the  tops  of  the  taller 
trees.  Where  the  tops  cannot  be  reached  with  these,  the  men  climb 
into  the  trees  with  shorter  poles.  The  bamboo  poles  used  are  about 
24  feet  long  and  because  of  their  lightness  can  be  used  with  greater 
speed.  Bamboo  poles  with  short  internodes  should  be  selected  as 
they  are  less  likely  to  break.  Breakage  may  also  be  reduced  by  stor- 
ing the  poles  in  a  cool  place  where  drying-out  will  not  be  excessive. 

The  sheets  used  are  made  of  duck  ranging  in  weight  from  7  to  12 
ounces.  Sizes  of  single  sheets  range  from  12  X  24  to  24  X  48  feet. 
Sheets  need  not  be  much  longer  than  the  longest  diameter  of  the  tree. 
To  prevent  mildew  and  rotting  of  the  fabric  in  the  sheeets  they  should 
be  boiled  in  a  solution  of  tannin  before  being  used.  The  life  of  sheets 
thus  treated  will  be  greatly  lengthened. 

A  number  of  growers  have  provided  special  contrivances  by  which 
sheets  are  mounted  on  sleds  or  wheels  so  they  are  not  dragged  on  the 
ground.  The  principal  objection  to  such  an  arrangement  is  that 
the  sled  or  wheeled  frame  must  be  made  in  two  sections,  one  for  each 
side  of  the  tree,  thus  increasing  the  cost  of  the  operation  because  the 
horses  can  be  used  for  nothing  else  while  harvesting  is  in  progress. 
On  the  other  hand,  by  the  dragging  process  sheets  will  not  last  more 
than  two  or  three  seasons,  whereas  by  the  sled  or  wagon  method  they 
will  last  from  six  to  ten  years  longer.  The  two  wagons  shown  in 
figure  21,  each  12  X  24  feet,  cost  between  $60  and  $70,  about  1914. 
The  canvas  portion  is  of  8-ounce  duck.  By  this  method  the  knockers 
can  gather  ten  lug  boxes  before  emptying.  The  work  can  be  done 
much  faster  with  wagons.  With  the  sleds  a  sheet  is  fastened  length- 
wise on  the  right-hand  side  of  one  and  another  on  the  left-hand  side 
of  the  other  sled. 

Hulling. — After  harvesting,  the  almonds,  hulls  and  all  are  taken 
while  still  moist,  to  the  huller  to  separate  them.  If  they  become  dry 
before  hulling  they  must  be  dipped  in  water  or  the  shells  will  be 
broken.  All  hulling  was  formerly  done  by  hand,  and  this  is  still  done 
where  only  small  lots  are  to  be  handled.  The  invention  of  machinery 
for  this  purpose  has  reduced  the  cost  of  hulling  from  60  to  80  per 
cent,  for  most  outfits  separate  the  hulls  from  the  nuts  before  they 


THE   ALMOND   IN   CALIFORNIA 


43 


leave  the  machine.  Some  of  the  hand  hullers  consist  simply  of  the 
hulling  portion  of  the  large  power  machines  without  the  separating 
screens.  These  cost  about  one-sixth  or  one-seventh  as  much  as  the 
large  machines,  and  where  a  man  has  a  small  acreage  and  is  too  far 
away  to  haul  to  a  large  huller,  <i  hand  machine  will  greatly  facilitate 
the  work,  even  though  the  final  separation  must  be  done  by  hand. 

There  are  three  different  kinds  of  hulling  and  separating  machines 
now  in  operation  in  California,  all  invented  by  California  almond 


Fig.  21. — Portable  almond  sheets  mounted  on  wheels  as  used  by  N.  J.  Lund, 
Oakdale,  California,  1916. 

growers.  The  first  one  made  was  the  Read  "Sure-Pop"  almond 
huller.  This  is  now  manufactured  in  three  sizes  by  the  Sehmeiser 
Manufacturing  Company,  Davis,  California.  The  No.  3  huller  does 
not  have  any  separating  device  and  is  generally  best  for  orchards  of 
less  than  ten  acres.  It  may  be  operated  by  hand  or  by  a  small  engine 
or  motor.  The  No.  2  hullers  both  hull  and  separate  and  are  operated 
only  by  power.  They  should  pay  in  orchards  of  ten  acres  or  more. 
The  No.  1  is  the  largest  made  and  is  for  use  in  large  orchards  of  100 
acres  or  more. 

The  Beach  huller  is  of  more  recent  origin,  having  been  in  use  only 
since  1895.  It  was  invented  by  J.  E.  Beach  of  Fairoaks,  California, 
and  is  being  manufactured  by  him.  The  two  sizes  of  this  machine  are 
both  power  outfits;  they  are  doing  satisfactory  work  at  the  present 
time. 


44  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

The  third  huller  is  that  made  by  C.  U.  Reams  of  Suisun.  One  of 
the  first  machines  made  by  him  was  in  1897,  and  is  now  in  working 
order  at  the  F.  0.  Scarlett  ranch,  northeast  of  Suisun,  and  is  doing 
satisfactory  work.  Since  the  first  invention,  Reams  has  made  a  num- 
ber of  improvements  both  in  the  method  of  hulling  and  of  separating. 

Many  growers  do  not  have  sufficient  tonnage  to  enable  them  to 
afford  a  commercial  huller,  and  yet  hulling  by  hand  is  a  slow  and 
tedious  practice.  C.  E.  Sedgwick,  Manager  of  the  Solano  District  of 
the  Pacific  Gas  and  Electric  Company,  located  at  Dixon,  California, 
conceived  the  idea  of  using  a  centrifugal  blower  operated  by  a  small 
electric  motor  to  do  the  hulling.  His  description  of  this  outfit,  quoted 
from  "Pacific  Service  Magazine,"  April,  1916,  page  393,  after  making 
two  small  corrections  given  by  Mr.  Sedgwick,  is  as  follows : 

The  equipment  consists  of  a  No.  0  Sturtevant  exhaust  fan  belted  to  a  1  h.p. 
motor.  The  nuts  are  fed  into  the  suction  side  of  the  fan  where  they  are  picked 
up  by  the  runner,  hurled  against  the  casing  of  the  fan  and  blown  out  of  the  dis- 
charge into  a  box. 

The  motor  consumes  three-tenths  kilowats  when  almonds  are  fed  into  the  fan 
at  the  rate  of  a  lug  box  every  minutes  and  one-half,  so  that  the  power  cost,  even 
at  the  8-cent  lighting  rate,  is  only  2.4  cents  per  hour.  The  fan  costs  about  $20, 
while  the  regular  commercial  hullers  run  as  high  as  $750. 

Further  inquiry  from  Mr.  Sedgwick  developed  the  fact  that  this 
huller  has  operated  for  three  seasons  on  a  20-acre  almond  orchard. 
Peerless,  Drake  and  I.X.L.  almonds  were  all  hulled  successfully.  Non- 
pareils have  not  as  yet  been  tried.  The  speed  most  commonly  used 
was  about  1200  r.p.m.,  though  it  varied  somewhat  with  the  different 
varieties.    He  believes  that  a  larger  size  would  do  better  work. 

The  efficiency  of  any  of  the  above  hullers  depends  largely  upon  the 
speed  of  the  machine  and  upon  the  condition  of  the  almonds  in  the 
hulls.  If  the  machine  runs  too  fast  the  almonds  will  be  broken  and 
injured,  and  if  it  runs  too  slowly  many  of  the  almonds  are  not  hulled. 
If  the  almonds  are  allowed  to  hang  on  the  trees  too  long,  or  if  allowed 
to  lie  around  too  long  after  being  harvested,  the  hulls  become  dry  and 
leathery  and  the  difficulty  of  hulling  is  greatly  increased.  Dipping 
in  water  in  such  cases  may  help  to  overcome  this  difficulty  to  a  limited 
extent. 

The  papershell  varieties,  notably  the  Nonpareil,  are  much  more 
difficult  to  hull  without  breaking  the  shells  than  are  the  harder  shelled 
varieties.  The  Nonpareil  hull  has  a  tendency  to  close  around  the  nut 
on  drying,  making  hulling  under  such  circumstances  very  difficult. 

Often  when  the  moisture  supply  in  the  soil  is  exhausted  before  the 
nuts  are  ripe,  or  where  the  loss  of  leaf  surface  due  to  mites  is  serious 


THE   ALMOND   IN   CALIFORNIA  45 

prior  to  ripening,  the  hulls  open  only  slightly  or  not  at  all,  but  dry 
onto  the  shell  of  the  nut.  Such  "sticktights"  can  only  be  disposed 
of  profitably  by  allowing  them  to  thoroughly  dry,  when  they  are 
cracked  and  sold  as  kernels. 

After  the  hulling  operation  all  almonds  must  be  gone  over  by 
hand  to  remove  pieces  of  hulls  and  inferior  or  gummy  nuts.  Where 
canvas  drapers  are  not  available  for  sorting  directly  from  the  huller, 
the  nuts  are  piled  in  hoppers  and  sorted  on  benches  beneath  them. 

Drying. — Immediately  following  the  sorting,  the  nuts  are  spread 
on  trays  and  thoroughly  dried  in  the  sun.  In  the  interior  valleys 
during  the  hot,  dry  weather  the  nuts  will  sometimes  dry  so  quickly 
that  by  the  time  the  sorting  from  hoppers  is  completed  the  nuts  are 
sufficiently  dry  to  be  bleached.  The  grower  must  be  certain,  however, 
that  such  is  the  case  before  any  bleaching  is  done,  or  before  the 
almonds  are  delivered  to  the  warehouses  for  bleaching.  The  nuts  are 
sufficiently  dry  when  the  kernels  will  break  without  bending.  Quick 
drying  is  essential  to  prevent  the  excessive  darkening  of  the  shell. 

Bleaching. — When  thoroughly  dry  the  nuts  are  ready  for  bleach- 
ing. The  shells  are  first  moistened  by  spraying  with  water  or  subject- 
ing them  to  low-pressure  steam  for  10  to  20  minutes.  The  shells  are 
then  subjected  to  the  fumes  of  burning  sulphur  for  10  to  30  minutes. 
The  sulphur  fumes  are  absorbed  by  the  moisture  on  the  shells,  which 
are  bleached  to  a  bright  yellow  color.  After  bleaching  the  nuts  are 
exposed  to  the  air  for  a  few  moments  to  allow  them  to  dry.  The 
market  demands  a  nut  that  has  been  sufficiently  bleached  to  give  it  a 
bright,  clean,  yellow  color.  An  over-bleached  almond  is  equally 
objectionable  because  of  its  pale,  sickly,  yellow  or  whitish  color. 
Over-steaming  or  sulphuring  permits  excessive  penetration  of  the 
sulphur  fumes,  with  the  resulting  danger  of  absorption  by  the  kernel. 
While  this  may  not  be  noticeable  in  the  flavor,  it  will  eventually  result 
in  premature  deterioration  in  the  form  of  rancidity.  Unbleached 
almonds  remain  edible  much  longer  than  bleached  almonds  in  nearly 
every  case.  Ordinarily  one  to  three  pounds  of  the  best  flowers 
of  sulphur  is  required  to  bleach  a  ton  of  almonds.  Lump  sulphur  is 
not  satisfactory. 

Sacking. — During  the  preliminary  handling  of  almonds  ordinary 
grain  sacks  are  commonly  used.  After  bleaching,  in  which  condition 
they  are  ready  for  market,  they  are  put  in  standard  almond  bags, 
measuring  20  X  40  inches  and  weighing  IVi  pounds.  The  weight  of 
a  bag  of  almonds  will  vary,  depending  not  only  on  the  variety  but  also 
on  the  year  in  which  the  crop  was  grown  and  the  locality  in  which  it 
was  produced.    For  selling  purposes  the  California  Almond  Growers' 


46  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

Exchange  estimates  weights  of  different  varieties  to  be  as  follows: 
Nonpareil  about  85  pounds  to  the  bag;  I.X.L.  about  80  pounds;  Ne 
Plus  Ultra,  75  pounds;  Drake,  90  to  100  pounds;  Languedoc,  100 
pounds ;  and  hardshell  almonds,  100  to  120  pounds. 

Shelling. — Within  the  past  two  years  the  shelling  of  almonds  has 
taken  a  prominent  place  in  the  consideration  of  the  men  charged  with 
the  disposal  of  the  almond  crop.  The  increasing  popularity  of  shelled 
almonds,  and  the  limited  market  for  unshelled  almonds,  makes  the 
production  of  more  shelled  almonds  imperative  in  view  of  the  pros- 
pects of  greatly  increased  production  in  the  next  few  years.  A  small 
proportion  of  the  shelled  almonds  marketed  are  those  accidentally 
shelled  during  the  hulling  process.  This  probably  averages  less  than 
30  pounds  per  ton  of  almonds  hulled  in  ordinary  years. 

The  varieties  most  commonly  shelled  are  the  papershells.  They  are 
much  more  easily  shelled  without  breaking  the  kernels  than  are  the 
harder  shelled  varieties  and,  in  addition,  are  worth  more  for  shelling 
because  of  the  high  percentage  of  kernel  compared  to  shell. 

Grading. — Grading  almonds  for  size  is  not  done  at  present  but 
probably  will  be  within  the  next  few  years.  Grading  for  quality  is 
done  regularly  by  testing  an  entire  lot  rather  than  attempting  to 
separate  inferior  nuts.  The  standard  grade  consists  of  all  lots  having 
the  required  percentage  of  good  kernels,  free  from  worms  or  gummy 
nuts.  This  requirement  varies  between  90  and  95  per  cent,  depending 
on  the  condition  of  the  crop  as  a  whole  and  on  the  market  conditions. 
The  standard  grade  of  a  given  variety  sells  on  guarantee  that  it  shall 
be  up  to  advertised  standard.  All  lots  which  cannot  pass  this  are  sold 
on  sample,  and  therefore,  on  their  own  individual  merits. 

MARKETING 

The  marketing  of  the  California  almond  crop  is  at  present  on  a 
firmer  basis  than  at  any  time  in  the  past.  Previous  to  1910  there  was 
little  or  no  cooperation  among  growers  and  the  buyers  had  everything 
their  own  way.  In  May  of  that  year,  however,  Mr.  J.  P.  Dargitz,  an 
almond  grower  near  Acampo,  California,  successfully  organized  the 
California  Almond  Growers'  Exchange,  consisting  of  nine  local  asso- 
ciations with  a  total  membership  of  230  growers.  The  Exchange 
started  business  with  $1000  borrowed  capital,  personally  guaranteed 
by  the  directors.  On  June  1,  1918,  there  were  22  sub-associations 
representing  about  2000  growers,  controlling  about  three-fourths  of 
the  crop.  The  Exchange  now  is  not  only  out  of  debt  but  owns  invest- 
ments aggregating  $100,000  in  value,  including  warehouses,  a  central 
shelling  plant  and  other  property.     At  the  same  time,  the  growers 


THE   ALMOND   IN   CALIFORNIA  47 

have  been  receiving  about  .50  per  cent  more  for  their  almonds  than 
before  the  Exchange  was  organized. 

The  success  of  the  Exchange,  with  the  consequent  higher  prices  to 
the  grower,  has  resulted  in  a  large  increase  in  the  acreage  of  almonds 
in  California.  This  increase  is  making  it  necessary  to  develop  new 
markets  to  absorb  the  greater  tonnage,  and  this  can  only  be  done 
effectively  or  satisfactorily  by  cooperative  effort. 

Heretofore,  California  almonds  have  been  marketed  chiefly  in  the 
shell.  A  small  proportion  has  been  cracked  annually  to  supply  western 
brokers  and  confectioners,  and  practically  all  of  these  have  been  sold 
west  of  the  Rocky  Mountains.  Only  the  whole  nuts  have  been  shipped 
to  the  eastern  markets. 

The  European  crops  are  sent  to  the  United  States  largely  as  kernels 
and  have  had  a  practical  monopoly  of  the  six  lied  almond  business 
east  of  the  Rockies.  The  Tarragonas  and  Valencias  shipped  to  Amer- 
ica come  into  direct  competition  with  the  I.X.L.,  Drake,  Languedoc 
and  other  California  almonds,  all  of  which  are  unshelled  for  the 
eastern  markets.  The  imports  of  unshelled  almonds  average  about 
the  same  as  the  California  production.  The  Jordan,  Princess  and 
other  varieties,  however,  come  in  shelled,  constituting  the  bulk  of  the 
importations.  The  Jordan,  because  of  its  superior  quality,  is  in  a 
class  by  itself  and  does  not  compete  at  present  with  the  California 
product.  The  Princess  and  other  almonds  of  that  type  are  much  the 
same  as  the  California  shelling  varieties  and  will  be  serious  competitors 
when  sold  in  the  same  markets.4 

Storing. — Almonds  awaiting  removal  or  sale  will  become  rancid 
if  stored  in  warm  or  clamp  places.  If  the  almonds  have  been  properly 
cared  for  during  the  handling  process  to  prevent  worm  infection,  and 
if  the  nuts  have  been  thoroughly  cured,  they  will  keep  satisfactorily 
for  a  year  or  more.  The  ideal  condition  is  to  keep  them  stored  in  a 
uniformly  cool,  dry  storage  place  with  ample  ventilation. 

YIELDS 

The  yield  of  almonds  in  different  years  and  in  different  orchards 
is  probably  more  variable  than  that  of  any  other  of  the  common 
orchard  fruits.  The  fluctuations  from  year  to  year  are  largely  due 
to  climatic  conditions,  while  the  variations  in  different  orchards  are 


*  Just  what  conditions  will  exist  after  the  close  of  the  present  war  cannot  be 
forecast  with  any  degree  of  accuracy.  One  thing  is  certain,  the  increasing  popu- 
larity of  shelled  almonds  mak<M  it  essential  that  the  American  markets  become 
familiar  with  the  California  shelled  product,  and  that  this  trade  be  extended  as 
quickly  as  possible. 


48  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

largely  due  to  variety,  care  given  the  trees  throughout  their  life,  the 
character  of  the  soil,  and  location  with  relation  to  local  frost  con- 
ditions. 

Almonds  first  commence  bearing  at  from  two  to  four  years  of 
age;  the  first  crop  ranging  from  one  or  two  nuts  up  to  a  hatful  or 
possibly  more.  The  trees  will  first  commence  to  bear  a  crop  which 
it  will  pay  to  harvest,  at  from  three  to  five  years  of  age.  Ordinariby, 
it  will  be  nearer  the  latter,  depending  upon  the  type  of  soil  in  which 
the  trees  are  growing  and  the  moisture  conditions  surrounding  them. 
On  the  hill  lands  the  trees  begin  to  mature  much  earlier  than  in  the 
rich  bottom  lands  and  consequently  come  into  bearing  earlier.  It 
must  be  borne  in  mind  that  a  crop  which  it  will  pay  to  harvest  does 
not  necessarily  pay  for  the  cost  of  orchard  maintenance.  A  crop  is 
not  considered  a  paying  crop  until  it  pays  for  the  cost  of  maintenance 
as  well  as  harvesting  and  handling.  Almond  orchards,  as  a  rule,  reach 
this  point  at  from  five  to  seven  years  of  age.  From  this  time  on  the 
trees  should  continue  to  increase  in  production  from  year  to  year, 
allowing  for  failures  due  to  frost  and  other  unfavorable  conditions, 
until  they  are  from  12  to  20  years  old.  Under  the  common  methods 
of  care  that  most  orchards  receive,  the  trees  commence  to  decrease  in 
their  production  at  from  25  to  30  years,  although  in  some  cases  it  will 
be  even  sooner  than  that.  On  the  other  hand,  well  cared-for  orchards 
will  continue  their  maximum  production  even  longer.  The  age  at 
which  an  orchard  will  no  longer  pay  will  range  from  30  years  upward. 
The  top  limit  is  still  unknown. 

Investigations  carried  on  during  1913-19145  brought  out  the  fol- 
lowing facts :  The  average  production  of  almonds  in  California  is 
between  700  and  800  pounds  per  acre ;  if  care  is  exercised  in  the 
selection  of  a  proper  location  for  an  orchard  and  if  good  judgment  is 
used  in  managing  it,  1000  pounds  per  acre  would  be  a  safe  estimate  for 
business  purposes ;  in  many  years  competent  men  might  be  expected  to 
obtain  1500  pounds  per  acre,  but  this  could  not  be  expected  to  hold 
for  a  ten-year  average.  The  possibilities  are  shown  by  the  crop  from 
one  acre  on  the  University  Farm,  at  Davis,  California,  of  ten-year-old 
trees  which  amounted  to  nearly  2800  pounds  in  1917. 

COST  OF  PRODUCTION 

The  cost  of  producing  almonds  involves  a  number  of  variable 
factors,  including  overhead  charges,  such  as  the  cost  of  the  land, 
equipment,  taxes,  insurance  and  depreciation ;  and  also  the  cost  of 
maintenance  and  handling.    Maintenance  includes  such  costs  as  prun- 

5Cir.  121,  Univ.  Calif.  Agri.  Exp.  Station,  October,  1914. 


THE   ALMOND   IN   CALIFORNIA  49 

ing,  plowing,  cultivating,  spraying  and  irrigation.  Handling  includes 
harvesting,  hulling,  hauling,  and  warehousing.  Tabulations  of  esti- 
mates in  tables  II  to  VIII  are  based  on  information  collected  during 
the  years  1913  to  1916,  inclusive,  from  a  large  number  of  growers  in 
practically  all  the  almond  districts  of  the  state,  and  represent  as 
accurately  as  possible  with  the  data  at  hand  the  average  costs  which 
actually  exist  throughout  California. 

Cost  of  the  Land. — The  estimates  given  in  table  II  are  to  be  taken 
as  only  partially  indicative  of  conditions  which  actually  exist  in  the 
various  districts  mentioned.  These  figures  do  not  give  the  entire  range 
of  prices  but  indicate  some  of  the  more  common  values  placed  upon 
the  land. 

TABLE  IT 

Value  of  Almond  Land  in  California 

Land  in  bearing 

District —  Ban-  land  orchard 

Best  Sacramento  Valley  land $200-$400  $400-$600 

Other  good  interior  valley  lands 150-  300  400-  500 

Sacramento  Valley,  foothill  sections 75-  150  200-  400 

Contra   Costa  County..... 100-  300  250-  500 

Santa  Clara  and  San  Benito  counties 300-  600  500-  800 

Paso   Bobles   district _ 50-  150                          

Banning  district  400-  800  600-1000 

Averages    for    California $250  $500 

Equipment. — It  has  been  found  impossible  to  gather  accurate  figures 
upon  cost  of  equipment  in  almond  orchards,  and  especially  so  in  view 
of  the  present  abnormal  economic  conditions,  but  the  list  given  in 
table  III  will  give  an  idea  of  the  equipment  required.  In  addition, 
there  will  be  other  small  items  the  grower  will  need  which  are  not 

mentioned  here. 

TABLE  III 
Almond  Orchard  Equipment 

Plows  Harvesting   equipment : 
Harrows    (spike-tooth   and   spring-  Almond  sheets 

tooth)  Poles 

Disc  Cultivator  Lug  boxes 

Weed  cutter  Hulling  machine 

Clod  masher  Sorting  tables  and  bins 

Boiler  Drying  trays 

Hoes,  shovels,  etc.  Sacks  for  transportation  to  ware- 

Pruning  tools  house. 

Brush  burner  Orchard  heating  equipment    ($25-$30 
Spray  outfit  per  acre) 

Wagon  Horses  or  tractors 

Barns,  sheds  and  other  buildings  Harness 


50  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Average  Overhead  Charges. — Table  IV  shows  the  average  overhead 
charges  for  almond  orchards.  Interest  and  depreciation  on  buildings 
are  not  included  because  of  the  great  variation  in  their  character,  so 
that  an  extra  charge  must  be  figured  on  these  items  by  the  individual 
grower. 

TABLE  IV 
Average  Overhead  Charges  per  Acre 

Taxes  and  insurance $4.00 

Interest    30.00 

Depreciation   on   working   equipment 4.00 

Total    $38.00 

Cost  of  Production. — Table  V  shows  the  average  cost  of  production 
for  bearing  orchards  of  varieties  in  all  districts,  based  on  personal 
observation  and  cost  records  from  a  large  number  of  orchards  men- 
tioned previously.  Wherever  cost  is  dependent  upon  tonnage  the 
average  yield  of  700  pounds  per  acre  is  used  as  the  basis  for  computa- 
tion. Depreciation  on  buildings  and  trees,  time  spent  by  teams  in 
idleness,  feed  consumed  during  such  times  and  other  minor  items  are 
too  variable  to  safely  estimate,  but  must  be  considered. 

TABLE  V 
Average  Cost  of  Production  of  all  Bearing  Orchards  in  California 

Maintenance :  Per  acre 

Pruning $3.00 

Plowing  2.75 

Harrowing .75 

Cultivation  and  weed  cutting 3.00 

Spraying   3.00 

Irrigation 2.00 

Handling : 

Harvesting,  hulling,  etc 20.00 

Warehousing  (including  bleaching),  @  ^c  per  lb 1.75 

Miscellaneous  expense  for  maintenance  and  handling 2.00      $38.25 

Overhead   charges   38.00 


Total  cost  per  acre $76.25 

Cost  per  pound  for  maintenance  and  handling $0,055 

Cost  per  pound  for  overhead  charges 0.054 

Total  cost  per  pound $0,109 


THE   ALMOND   IN    CALIFORNIA  51 

Returns, — Prices  paid  to  growers  have  fluctuated  considerably,  due 
to  the  great  variation  in  both  the  California  and  European  crops  from 
year  to  year.  Table  VI  shows  the  average  prices  per  pound  paid  to 
the  growers  for  the  four  principal  varieties  marketed  through  the 
Exchange  since  its  organization. 

TABLE  VI 

Net  Prices  Eealized  by  the  Exchange  Members  for  Different  Varieties  for 

the  Years  1910  to  1916,  Inclusive,  in  Cents  PE:t  Pound 

Ne  Plus 

Year  Nonpareil  I.X.L.  Ultra 

1910 14.00  13.00  12.00 

1911 16.50  15.50  14.50 

1912 13.25  12.25  11.25 

1913 17.25  16.25  15.25 

1914 18.00  15.00  14.50 

1915 13.00  12.00  11.00 

1916 17.25  14.75  13.75 


Drake 

Crop 
tons 

10.00 

3,500 

12.00 

1,450 

9.50 

3  000 

13.25 

1,100 

11.50 

2,250 

9.25 

3,500 

13.00 

3,400 

Average....      15.61  14.11  13.18  11.22  2,571.4 

Table  VII  shows  the  average  price  per  pound  paid  to  the  growers 
for  all  almonds  (unshelled)  regardless  of  quality  and  variety,  based 
upon  the  entire  crop  handled  by  the  Exchange  during  the  years 
1910  to  1916,  inclusive.  Prom  these  figures  the  average  return  per 
pound  for  all  varieties  for  seven  years  based  on  the  crop  tonnage 
for  each  year,  1910  to  1916,  inclusive,  has  been  found  to  be  13.09  cents 
per  pound. 

TABLE  VII 

Average  Prices  per  Pound  Paid  Growers  for  all  Unshelled  Almonds  for 

the  Years  1910  to   1916,  Inclusive 

Price  per  pound.  California  crop. 

Year  cents  tons 

1910 12.0  3,300 

1911 13.5  1,450 

1912 11.0  3,000 

1913 15.5  1,100 

1914 14.05  2,250 

1915 10.75  3,500 

1916 13.97  3,400 

Average 13.09  2,571.4 

The  relation  of  yields,  returns  and  profits  from  the  growers '  stand- 
point is  one  which  every  person  must  consider  before  entering  the 
business.  In  view  of  the  extravagant  claims  which  have  been  made  as 
to  the  enormous  profits  realized  by  the  average  grower,  the  figures  in 


52  UNIVERSITY    OP    CALIFORNIA — EXPERIMENT    STATION 

tables  II  to  VIII  have  been  worked  out  and  presented  here.  The 
summation  of  the  relation  of  yields,  returns  and  cost  of  production 
to  the  profits  for  the  average  grower  of  almonds  is  shown  in  table  VIII. 

TABLE  VIII 

Belation  of  Average  Yields,  Costs  and  Beturns,  to  Profits 

Average  yield  per  acre 700  pounds 

Average  returns  to  grower  per  acre $97.30 

Average  cost  of  production  per  acre 76.23 

Average  profit  per  acre $21.05 

Depreciation  on  buildings  and  trees,  and  other  unfigured  costs,  are 
too  variable  to  estimate,  but  they  must  come  from  these  profits. 

DISEASES 

Crown  Gall. — Also  commonly  known  as  root-knot.  This  disease  is 
one  of  the  most  serious  with  which  the  grower  has  to  contend.  It  is 
found  practically  everywhere  almonds  are  grown  and  either  greatly 
reduces  the  vitality  of  or  kills  the  trees  affected,  depending  upon  the 
seriousness  of  the  attack. 

The  disease  is  caused  by  a  bacterial  organism,  Bacterium  tume- 
faciens,  that  seems  to  be  native  to  most  California  soils.  It  is 
characterized  by  large  swellings  on  the  root  crown  or  main  roots  just 
below  the  surface  of  the  ground,  though  lesser  infections  may  some- 
times be  found  also  on  the  smaller  roots.  When  cut  open,  these  knots 
appear  spongy  as  if  the  bark  and  wood  were  all  mixed  together  in  one 
mass.  They  are  most  serious  when  spread  over  a  large  surface,  either 
partially  or  completely  girdling  the  root  or  crown  of  the  tree. 

Control  methods  are  of  three  kinds : 

(1)  Plant  nothing  but  clean,  healthy  nursery  trees,  free  from  all 
trace  of  galls.  In  planting  these  trees  be  careful  to  trim  off  all  broken 
or  injured  roots,  leaving  nothing  but  smooth  clean  cuts  at  the  ends 
of  the  roots  which  will  heal  over  readily  with  the  minimum  oppor- 
tunity for  infection. 

(2)  Galls  on  orchard  trees  may  be  cut  out  to  clean,  healthy  wood 
with  a  sharp  knife  or  gouge  chisel.  The  wound  should  be  thoroughly 
disinfected  with  a  strong  copper-sulphate  or  corrosive-sublimate  solu- 
tion, and  painted  with  a  protective  covering  such  as  paint  or  melted 
asphaltum,  or  it  may  be  covered  directly  with  Bordeaux  paste  and 
then  the  earth  returned  to  its  place  over  the  roots. 

(3)  A  method  used  with  apparent  success  is  to  bore  a  one-inch  hole 


THE   ALMOND   IN   CALIFORNIA  53 

about  two-third  of  the  way  through  each  gall,  as  soon  as  the  trees  have 
become  dormant  in  the  fall.  Then  fill  each  hole  with  a  concentrated 
solution  of  copper  sulphate  and  plug  the  opening.  By  spring,  when 
growth  is  ready  to  start,  the  gall  may  be  knocked  off  with  a  hammer. 
In  most  cases  the  gall  is  so  thoroughly  permeated  by  the  solution  that 
the  infection  is  completely  killed  and  further  gall  growth  ceases  in 
that  place,  unless  later  infection  occurs. 

The  use  of  resistant  stocks  has  been  suggested  as  a  means  of  avoid- 
ing infection,  but  no  such  stock  suitable  for  the  almond  has  yet  been 
proved  to  be  sufficiently  resistant  under  average  conditions  to  be 
safely  recommended.  The  greatest  hopes  for  future  success  in  com- 
bating this  disease,  however,  lie  along  this  line. 

Oak  Fungus, — This  is  one  of  the  most  difficult  diseases  to  control 
because  it  works  and  spreads  beneath  the  surface  of  the  ground  in 
the  roots  of  trees.  In  some  sections  of  the  state  it  is  very  serious  in 
many  orchards. 

The  disease  is  often  known  as  root-rot,  being  caused  by  a  fungus 
Ar miliaria  mellea,  commonly  called  "toadstool"  fungus.  It  is  known 
as  Oak  fungus  because  the  disease  is  most  commonly  found  in  spots 
where  old  oak  trees  have  stood.  Where  orchards  have  been  planted 
on  such  land,  spots  appear  in  which  the  trees  gradually  dre,  the  disease 
spreading  from  tree  to  tree,  in  ever-widening  circles,  involving  ordi- 
narily about  one  row  of  trees  each  year.  During  the  winter,  clusters 
of  toadstools  may  be  seen  at  the  base  of  the  affected  trees.  The  fungus 
lives  over  in  the  old  oak  roots  for  many  years  and,  as  the  orchard 
becomes  well  established,  the  fungus  spreads  to  the  almond  roots.  If 
not  checked  the  spot  will  eventually  involve  the  entire  orchard  and 
prevent  further  growth  of  almonds  on  such  land  for  many  years. 

Control  is  very  difficult  but  may  be  secured  by  digging  a  deep 
trench  around  the  affected  area  and  preventing  the  infection  from 
passing  beyond  through  the  roots.  The  spread  of  the  disease  may 
sometimes  be  held  in  check  by  grubbing  out  a  row  or  two  of  healthy 
trees  outside  the  affected  area  and  taking  care  that  all  of  the  large 
roots  are  removed  to  a  depth  of  several  feet.  Carbon  bisulphide  has 
been  suggested  for  killing  the  fungus,  but  the  cost  is  prohibitive  except 
in  small  spots  just  starting. 

There  are  no  resistant  stocks  known  at  present  upon  which  the 
almond  can  be  worked.  The  fig,  pear  or  black  walnut  might  safely 
replace  the  almond  in  such  spots. 

Shot-hole  Fungus. — There  are  three  different  fungi  that  produce 
the  shot-hole  effect  on  the  leaves  of  the  almond,  thus  giving  rise  to  the 
name. 


54  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

(1)  Coryneum  bcyerinkii,  or  peach  blight,  is  the  most  common  form. 
It  is  not  as  serious  on  the  wood  of  the  almond  as  it  is  on  the  peach, 
but  in  seasons  of  damp  spring  weather  it  does  much  damage  to  the 
blossoms,  fruits  and  leaves.  Affected  blossoms  are  killed  outright,  the 
entire  blossoms  turning  brown  and  dropping  much  as  if  killed  by 
frost.  The  young  fruit  becomes  spotted  by  the  fungus  and  this  causes 
malformation,  gumming  and  shriveling  of  the  nuts,  varying  consider- 
ably with  the  severity  of  the  attack.  On  the  leaves  many  small  dead 
spots  appear,  the  dead  tissue  soon  falling  out  and  giving  the  shot-hole 
effect.  "Where  the  twigs  are  affected,  small  dead  spots  appear  during 
the  winter,  most  often  at  the  buds.  This  causes  the  death  of  the  buds 
and  often  the  ends  of  the  twigs.  During  the  spring,  after  growth 
starts,  considerable  gumming  occurs  from  these  spots. 

Effective  control  can  only  be  secured  by  two  sprays — Bordeaux 
mixture  in  the  fall,  as  soon  as  the  tree  becomes  dormant,  and  either 
Bordeaux  or  lime-sulphur  solution  (winter  strength)  just  before  the 
buds  open  in  the  spring.  Both  fall  and  spring  sprays  must  be 
thoroughly  applied  to  be  effective. 

(2)  Cercospora  circumscissa  is  another  fungus  causing  much  the 
same  effect  as  the  Coryneum.  It  is  difficult  for  an  untrained  person  to 
distinguish  between  them.  The  same  sprays  used  for  Coryneum  are 
effective  in  controlling  this,  though  if  this  form  alone  is  present  the 
Bordeaux  mixture  or  lime-sulphur  spray  in  the  spring  should  be 
sufficient. 

(3)  Gloeosporium  amygdalinum,  while  apparently  uncommon  in 
this  state,  has  been  found  to  exist  in  some  places.  Further  work  must 
be  done  on  this  to  determine  its  behavior  and  the  most  satisfactory 
methods  of  control,  but  it  is  believed  that  the  control  measures  men- 
tioned for  the  other  forms  of  "shot-hole"  will  also  be  applicable  to 
this. 

Prune  Rust  (Puccinia  Pruni). — This  fungus  is  worst  in  the  south- 
ern coast  sections  where  almonds  are  not  extensively  grown.  It  is  not 
serious  on  thrifty  trees  well  supplied  with  moisture.  The  disease  is 
characterized  by  reddish  pustules  on  the  under-sides  of  the  leaves, 
appearing  generally  about  July  or  August  and  causing  a  premature 
yellowing  and  dropping  of  the  leaves. 

Ordinarily  the  only  treatment  needed  is  to  supply  the  necessary 
moisture  in  the  soil  to  keep  the  trees  healthy  and  vigorous. 

Heart  Rot. — This  is  one  of  the  most  insidious  of  tree  diseases,  for 
it  works  inside  beneath  an  apparently  healthy  exterior  until  the  decay 
has  progressed  so  far  that  the  tree  commences  to  break  down,  and 
then  it  is  too  late  for  remedial  measures.     The  almond  is  not  as 


THE   ALMOND   IN   CALIFORNIA  55 

susceptible  to  this  as  most  other  kinds  of  orchard  trees,  but  where 
large  wounds  have  been  exposed  to  the  weather,  infection  may  take 
place  readily,  and  after  it  is  once  well  started  it  continues  at  a  com- 
paratively rapid  rate.  Decay  is  caused  in  most  cases  by  one  or  more 
of  about  a  dozen  different  fungi,  of  which  the  oyster-shell  fungus  is 
by  far  the  most  common. 

Control  consists  in  taking  care  to  leave  no  open  wounds  exposed 
to  the  air  to  dry  and  crack,  thus  permitting  the  entrance  of  decay 
organisms.  Much  of  this  can  be  avoided  by  care  in  pruning  the  young 
tree  so  that  the  removal  of  the  large  limbs  will  not  be  necessary  later 
on.  Where  such  wounds  must  be  made,  measures  should  be  taken  to 
prevent  infection.  This  can  best  be  done  by  making  smooth,  clean 
cuts  close  to  the  part  from  which  the  branch  to  be  removed  emanates, 
leaving  no  stub.  Stubs  dry  out  and  crack  more  quickly  and  require 
very  much  longer  to  heal  over,  if  this  is  possible  at  all.  Further,  all 
such  wounds  which  will  not  heal  over  the  first  season  should  be  covered 
with  some  good  disinfectant,  such  as  corrosive  sublimate,  one  part  to 
one  thousand  parts  of  water,  and  then  painted  over  with  some  elastic 
coating,  such  as  "Flotine"  or  asphaltum,  grade  D,  applied  with  a 
brush.  The  entire  wound  must  be  covered  or  the  work  is  largely 
wasted. 

Die-back. — This  is  serious  in  many  orchards  where  moisture  is 
insufficient  to  carry  the  trees  through  the  growing  season,  and  the 
trees  show  considerable  dying-back  of  the  branches.  Unfavorable 
soil  conditions,  such  as  hardpan,  gravel  or  sand  may  be  the  direct 
cause  of  such  moisture  shortage.  Lack  of  soil  fertility  is  also  a  com- 
mon cause.  Control  measures  consist  in  remedying  the  defective 
conditions  and  where  this  cannot  be  done  economically  it  is  better  to 
abandon  further  attempts  at  almond  culture  on  such  land. 

Sour-sap. — This  is  one  of  the  so-called  "physiological  diseases" 
and  is  quite  common  with  the  almond.  It  is  most  frequently  found 
where  trees  are  planted  in  heavy  or  poorly  drained  soils.  The 
inability  of  the  almond  to  endure  standing  water  around  its  roots  for 
any  length  of  time  and  particularly  so  after  growth  commences  in  the 
spring,  renders  it  especially  liable  to  sour-sap  when  planted  in  soils 
where  excess  water  from  the  late  winter  and  spring  rains  cannot  be 
readily  drained  away.  The  direct  cause  of  the  trouble  is  sudden 
changes  in  weather  from  warm  to  cold  after  growth  commences,  which 
checks  the  flow  of  sap  very  suddenly,  causing  stagnation,  cracking  of 
the  bark  and  then  fermentation.  With  an  unusually  strong  flow 
of  sap  in  trees  in  wet  soils,  such  climatic  changes  cause  unusually 
severe  disturbances  in  the  normal  functioning  of  the  -trees. 


56  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

The  affected  trees  ordinarily  show  the  disease  first  in  the  spring 
when  gum  may  be  seen  oozing  from  the  bark  of  the  .trunk  or  main 
branches,  and  sometimes  even  from  the  smaller  branches.  Small  or 
large  branches  may  die,  and  in  severe  cases  the  tree  may  die  soon  after 
having  commenced  to  leaf  ont  strongly.  On  cutting  through  the  bark 
to  the  wood  and  peeling  back,  a  strong  sour  odor  is  noticeable.  The 
cambium  layer  appears  brownish  or  reddish  in  color  and  often  masses 
of  gum  may  be  found  between  the  bark  and  the  wood.  Mild  cases 
may  not  be  serious  enough  to  show  on  the  outside  of  the  tree  and  only 
portions  of  the  cambium  layer  may  die.  The  sudden  dropping  of  the 
blossoms  or  young  fruit  may  in  some  instances  be  attributable  to 
sour-sap. 

All  affected  parts  on  smaller  branches  should  be  cut  back  to 
healthy  wood,  while  on  the  main  branches  or  trunk,  where  only  a 
small  portion  or  one  side  is  affected,  it  is  best  to  clean  out  the  dead 
bark  and  paint  the  bared  wood  with  a  protective  covering  until  new 
bark  can  cover  the  spot.  At  the  same  time  every  effort  should  be 
made  to  remedy  the  soil-moisture  conditions  which  were  largely 
responsible  for  the  trouble  in  the  first  place. 

Fruit-drop. — The  same  conditions  which  cause  sour-sap  may  cause 
fruit  drop.  It  may  be  caused  by  lack  of  pollination  due  to  improper 
mixing  of  varieties  or  to  rain  during  blossoming.  Frost  may  also 
produce  the  same  thing  by  killing  the  germ  in  the  young  fruit.  In 
such  cases,  the  fruit  may  remain  on  the  tree  for  one  or  two  weeks 
after  the  injury  occurs  before  falling,  and  in  some  cases,  may  even 
appear  to  continue  its  development  for  a  short  while. 

INSECT   PESTS 

Mites. — Commonly  called  red  spiders.  There  are  two  kinds  of 
mites  that  do  much  damage  in  almond  orchards,  the  brown  or  almond 
mite  and  the  yellow  or  two-spotted  mite.  Both  are  common  in  all 
parts  of  the  state  and  are  the  worst  pests  the  almond  grower  must 
regularly  face. 

The  brown  mite  {Bryobia  prai  em-is)  is  the  larger  of  the  two,  is 
dark  red  or  brown  in  adult  stage,  has  very  long  front  legs,  and  a 
flattened  back.  It  does  not  spin  any  web  and  works  on  the  green  bark 
of  the  small  twigs  as  well  as  on  the  leaves,  sucking  the  plant  juices 
from  beneath  the  bark.  It  causes  a  mottling  of  the  leaves  which  event- 
ually fall,  although  not  as  readily  or  in  such  large  numbers  as  when 
attacked  by  the  yellow  mite.  The  injury  to  the  tree  is  equally  as 
great  because  of  the  serious  drain  on  the  vitality  as  a  whole  and  be- 
cause it  commences  work  earlier  in  the  season.    This  mite  may  spend 


THE    ALMOND    IN    CALIFORNIA 


57 


Fig.  22. — Nonpareil  almonds.  Branch  on  left  free  from  Bed  Spider  and 
holding  its  full  supply  of  leaves  in  green,  healthy  condition;  branch  on  right 
defoliated  by  Yellow  Mite.  Note  premature  ripening  of  nuts  on  defoliated 
branch. 


58 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 


its  entire  life  on  the  tree;  the  very  small,  round,  red  eggs  being  laid 
largely  on  the  under-side  of  the  branches  and  in  cracks  and  crevices 
in  the  bark  and  twigs.  These  remain  on  the  tree  throughout  the  win- 
ter and  hatch  early  in  the  spring  soon  after  the  trees  have  their  leaves 
half  developed,  leaving  the  white  egg-shells  in  place.  Most  of  their 
work  is  done  in  the  spring  and  early  summer. 

The  brown  mite  may  be  controlled  satisfactorily  by  means  of  a 


Fig.  23. — Forty-three-year-old  Languedoc  almonds  on  peach  root,  near  Davis. 
This  orchard  has  not  been  thoroughly  cultivated  or  irrigated.  Mites  have  largely 
defoliated  the  trees.     See  contrast  in  Fig.  24. 

dormant  spray  of  lime-sulphur  solution,  1  gallon  to  10  gallons  of 
water,  applied  just  before  the  buds  open  in  the  spring.  Crude  oil 
emulsion  as  a  dormant  spray  is  also  effective,  if  thoroughly  applied 
over  the  entire  tree  under  high  pressure.  This  also  applies  to  appli- 
cations of  the  lime-sulphur  spray. 

During  the  growing  season  a  milder  material  must  be  used.  Dry 
dust  sulphur,  using  only  the  very  finest  grade  of  ' '  flowers  of  sulphur, ' ' 
is  often  very  effective,  provided  weather  conditions  are  satisfactory, 
but  generally  this  must  be  applied  a  number  of  times  if  best  results 
are  to  be  obtained.  The  work  is  done  by  blowing  \'.i  sulphur  dust 
into  the  tree  with  blowers  in  the  early  morning  when  there  is  little 
or  no  wind. 


THE   ALMOND   IN   CALIFORNIA 


59 


A  more  satisfactory  method  is  the  use  of  "Atomic  sulphur"  or 
oilier  sulphur  pastes  or  similar  material.  "Atomic  sulphur"  is  a 
prepared  spray  whose  value  consists  in  the  fact  that  the  sulphur  is 
held  in  suspension  in  water  so  that  it  may  be  applied  as  a  liquid  spray. 
By  this  method  the  material  may  be  more  effectively  and  thoroughly 
applied.  "Atomic  sulphur"  is  applied  at  the  rate  of  10  pounds  to 
100  gallons  of  water. 


N^£9tf| 

\ffi   ■&**' 'hi 

f 

p^ 

Ifi 

^PP 

% 

m 

.  '{■ 

,.  -  "fi 

r 
■  v    ■ 

K       '  ,■'  i 

&*!■ 

- 

' 

A 

-'•£,'.**  *w*-">W-       '- 

-J/j^-.^ 

IgW^r^v* 

^vr— 

■jl.  -  J?  iP^rf^fiJ 

mMBEZZZ- 

-  ■•■f 

Fig.  24. — -Forty-three-year-old  Languedoc  almonds  on  peach  root,  near  Davis. 
This  orchard  has  been  irrigated  and  thoroughly  cultivated,  and  mites  have  not 
defoliated  the  trees.     Note  contrast  in  Fig.  23. 

The  use  of  lime- sulphur,  the  commercial  strength  of  33  to  34 
degrees  Beaume  being  diluted  1  part  to  35  parts  water,  is  another 
effective  method.  For  such  use  a  flour  paste  may  be  added  at  the 
rate  of  4  gallons  to  each  100  gallons  of  the  spray  mixture  to  act  as  a 
spreader.  This  paste  is  made  by  cooking  one  pound  of  flour  with 
enough  water  to  make  one  gallon  of  the  mixture. 

The  yellow  mite  (Tetranychvs  telarius)  is  much  smaller  than  the 
brown  mite  and  is  of  a  pale  yellow  color  with  occasionally  a  reddish 
tinge  and  sometimes  with  two  darker  spots  on  either  side  of  the  body. 
Unlike  the  brown  mite,  the  winter  is  spent  in  concealment  somewhere, 
presumably  off  the  tree.     During  the  warm  days  of  early  summer, 


60  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

generally  in  June,  the  mite  makes  its  appearance  on  the  trees,  spin- 
ning a  fine  web  on  the  leaves,  generally  on  the  upper  surface,  and 
then  works  under  this  web.  The  mite  sucks  the  plant  juices  from 
the  leaves  giving  them  a  yellowish  mottled  appearance.  These  leaves 
soon  die  and  drop  to  the  ground.  In  serious  infestations  the  trees 
are  often  almost  completely  defoliated  by  the  end  of  August.  (See 
figure  22.) 

The  use  of  dormant  sprays  is  not  effective  for  controlling  the  yellow 
mite,  but  the  summer  sprays  mentioned  above  are  all  satisfactory,  and 
for  best  results,  must  be  applied  under  high  pressure,  preferably  200 
pounds  or  more. 

The  mites  are  much  easier  controlled  where  a  comparatively  high 
percentage  of  moisture  is  kept  in  the  soil  by  frequent  cultivations,  or, 
if  necessary,  by  irrigation  (figures  23  and  24). 

Peach  Tivig  Borer  (Anarsia  lineatella) . — In  the  larval  stage  these 
borers  work  on  the  young  buds  and  shoots  in  the  early  spring.  They 
are  especially  troublesome  in  newly  planted  orchard  trees  when  a  com- 
paratively small  number  may  kill  most  of  the  new  shoots  which  are 
needed  to  make  the  desired  framework  of  the  tree.  In  some  years  they 
may  be  serious  in  large  trees  also.  Dormant  spray  of  lime-sulphur 
applied  under  high  pressure  just  as  the  buds  are  opening  in  the  spring 
will  control  the  borers  very  effectively.  This  same  spray  way  be  used 
to  control  the  brown  mite,  thereby  accomplishing  double  control. 

California  Peach  Borer  {JEgeria  opalescens). — The  larvae  are 
serious  in  many  parts  of  the  state  where  they  burrow  just  under  the 
bark  near  the  surface  of  the  ground.  They  may  be  detected  by  the 
small  bits  of  frass  and  gum  at  the  entrance  of  their  burrows.  If 
allowed  to  continue,  they  will  eventually  girdle  the  tree. 

The  surest  means  of  control  is  to  dig  out  the  worms  with  a  knife 
or  kill  them  with  a  wire  probe.  This  work  should  be  done  sys- 
tematically once  or  twice  every  year  and  very  thoroughly  if  it  is  to 
be  effective.  The  application  of  hot  "Flotine"  or  asphaltum,  grade 
D,  after  the  worms  are  killed  should  help  considerably  to  prevent  the 
entrance  of  the  larvae.  To  be  effective  it  must  be  applied  at  least 
twice  a  year  on  young  trees  and  probably  the  same  on  old  trees. 

Thrips. — These  are  most  serious  on  the  almond  leaves,  their  attacks 
being  serious  enough  to  cause  considerable  defoliation  in  late  spring 
or  early  summer.  They  may  be  controlled  by  spraying  with  lime- 
sulphur,  1  to  30,  to  which  has  been  added  black-leaf  40  (40  per  cent 
nicotine)  at  the  rate  of  1  part  to  1500  parts  of  water  or  other  spray- 
mixture.     It  is  possible  that  other  than  the  pear  thrips  have  been 


THE    ALMOND   IN    CALIFORNIA 


61 


doing  damage,   but  the  same  spray   as  described   above  should   be 
effective  against  all. 

Grasshopper. — Grasshoppers  have  been  serious  in  orchards  in  out- 
lying foothill  districts  in  some  years,  and  especially  so  in  young 
orchards  where  it  has  been  almost  impossible  to  get  trees  started 
properly.  In  such  locations  special  means  must  be  employed  on  a 
large  scale  to  protect  orchards  from  their  devastations,  of  which 
poisoned  bait  and  hopper  dozers  are  the  most  effective. 


Fig.  25. — Almonds  infested  with  larvae  of   Indian  Meal   Moth    (Plodia 

interpunctella). 


Indian  Meal  Moth  (Plodia.  interpunctella). — The  larva  of  this 
moth  feeds  on  the  kernels  of  the  harvested  almonds  when  they  are 
stored.  Infestation  usually  takes  place  in  storerooms  or  warehouses 
in  which  the  nuts  have  been  placed  for  a  time.  The  warehouses 
become  infested  from  old  grain  bags  which  have  been  kept  there  at  one 
time  or  another.  So  far  as  known,  infestation  does  not  take  place  in 
the  field.  The  larvae  will  continue  to  work  in  the  stored  almonds  for 
a  long  time,  doing  a  very  great  amount  of  damage  (fig.  25).  They 
may  be  controlled  by  thoroughly  cleaning  out  the  corners  of  the  ware- 
house and  thoroughly  disinfecting.  The  nuts  should  be  disinfected 
with  carbon  bisulphide  (explosive  when  in  the  form  of  a  gas  mixed 


62  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

with  air),  or  other  means  used  to  control  insects  in  grain.6    Prevention 
is  far  easier  than  the  cure  in  this  case." 

Scale,  aphis,  diabrotica  and  other  insects  are  sometimes  found  on 
the  trees,  but  are  generally  not  sufficiently  troublesome  to  require 
special  attention.  Most  of  them  are  held  in  check  by  the  control 
measures  used  for  the  more  serious  pests. 

OTHER    PESTS 

Gophers. — These  often  do  great  damage  to  the  trees  by  girdling 
them  just  below  the  surface  of  the  ground,  or  if  they  do  not  actually 
girdle  the  trees,  they  cut  them  enough  to  devitilize  them  and,  in  addi- 
tion, the  wounds  made  by  their  gnawings  frequently  become  infected 
with  crown-gall  organisms.  The  only  safe  means  of  control  is  the 
constant  use  of  traps  supplemented  by  poisoned  bait. 

Squirrels. — Squirrels  are  very  troublesome,  as  they  harvest  a  large 
amount  of  almonds  before  they  are  sufficiently  ripe  to  be  harvested  by 
the  grower.  The  use  of  poisoned  grain  or  "gas,''  if  used  over  a  large 
area  of  surrounding  territory,  will  prevent  serious  depredations. 

Birds. — Birds  also  carry  off  large  amounts  of  almonds  if  the 
orchards  are  near  open  country  or  hills,  especially  if  wooded.  Crows, 
bluejays,  blackbirds,  yellow-hammers,  robins  and  other  similar  birds 
are  the  worst  offenders.  Sometimes  linnets  eat  off  large  numbers  of 
fruit  buds  in  the  spring  in  a  few  of  the  newer  sections  where  plantings 
are  scattered.  Sap-suckers  have  been  known  to  girdle  entire  trees  or 
large  branches  by  cutting  large  numbers  of  holes  in  a  series  of  lines 
close  together  around  the  trunk  or  limbs. 

Morning-glory. — This  is  probably  the  worst  of  the  weeds  in  almond 
orchards,  and  is  the  hardest  to  control.  Sheep  and  chickens  may  be 
used  with  excellent  results,  provided  care  is  taken  to  see  that  the  sheep 
are  not  allowed  to  go  hundry,  for  then  they  will  bark  the  trunks  of 
the  trees  very  quickly.  An  excellent  plan  is  to  arrange  gates  so  that 
the  sheep  must  go  through  the  orchard  from  pasture  to  get  water.  In 
passing  back  and  forth  they  will  forage  over  the  entire  orchard  and 
dig  up  all  the  morning-glory  in  sight.  Chickens  are  fond  of  the  suc- 
culent new  shoots,  and  will  keep  them  below  the  ground  until  the 
underground  stems  and  roots  weaken  and  die.  Cultivation  throughout 
the  growing  season,  often  enough  to  prevent  the  morning-glory  from 
developing  any  leaves  for  a  whole  year  at  least,  and  longer  if  neces- 
sary, will  starve  the  plants  to  death. 


6  The  fumigation  of  Stored  Grain,  Dried  Fruits,  and  Other  Products,  E.  E. 
DeOng,  Cal.  Agr.  Exp.  Sta.,  Dee.,  1917. 


THE    AliMOND   IN    CALIFORNIA  G.'i 


VARIETIES 

The  problem  of  selecting  varieties  of  almonds  for  planting  in 
California  is  to  choose  the  ones  that  are  most  marketable  and  at  the 
same  time  to  secure  best  results  in  cross-pollination.  At  the  present 
time  there  are  comparatively  few  varieties  of  almonds  which  have 
won  and  retained  their  popularity  with  the  grower  and  the  trade. 
There  are  a  number  of  reasons  for  this  condition.  The  cultural, 
climatic  and  soil  conditions  under  which  the  almond  thrives  are  much 
more  limited  than  for  most  of  the  common  deciduous  fruits ;  the  area 
of  production  in  America  is  limited  largely  to  California;  the  industry 
is  comparatively  new,  and  in  general,  there  is  not  the  great  varietal 
variation  in  season,  appearance,  texture,  flavor  and  behavior  that  is 
found  in  the  apple,  peach,  pear  and  similar  fruits.  The  comparatively 
rapid  deterioration  of  fleshy  fruits  after  ripening  makes  a  succession 
of  varieties  desirable  to  extend  the  period  of  consumption.  With 
almonds,  the  season  of  all  varieties  extends  from  one  harvest  to  the 
next,  if  properly  handled.  Growers  are,  therefore,  recommended  to 
plant  only  standard,  marketable  varieties  as  far  as  possible. 

Early  ripening  varieties  must  be  chosen.  The  crop  must  be  in 
the  hands  of  the  trade  early,  for  the  bulk  of  it  is  used  in  the  holiday 
trade.  This  is  especially  true  with  unshelled  almonds.  Early  almonds 
only  can  be  harvested  and  sold  before  the  bulk  of  the  European  ship- 
ments arrive. 

The  actual  time  of  ripening  of  the  different  varieties  is  variable 
from  season  to  season,  and  in  different  sections  or  even  different 
orchards  in  the  same  season.  Generally,  harvesting  commences  early 
in  August  and  closes  about  the  middle  of  October.  The  approximate 
order  of  ripening  of  the  better  known  varieties  is  shown  in  table  IX. 

TABLE  IX 
Approximate  Order  of  Eipening  of  Varieties  of  Almonds 

1.  Nonpareil  King 

2.  I.X.L.  Silver 
Jordan                                                         5.  Golden  State 

:!.  Ne  Plus  Ultra  (i.  Lewelling 

4.  Peerless  7.  Drake 

Princess  8.  Languedoc 

California  Texas 

Many  new  vareties  have  been  originated  in  California  but  most  of 
them  have  fallen  into  disfavor  in  a  short  time.  In  fact,  it  is  impossible 
to  locate  even  single  trees  of  some  varieties  which  were  formerly  well 


64  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

known.  From  time  to  time,  however,  worthy  varieties  have  been 
introduced  and  have  succeeded  in  making  a  permanent  place  for 
themselves  through  their  ability  to  fill  a  demand  that  before  had  been 
but  partially  or  poorly  supplied. 

In  view  of  the  changing  market  situation  for  California  almonds, 
due  to  the  rapidly  increasing  acreage  and  the  very  limited  demand 
for  unshelled  almonds,  it  is  safe  to  predict  that  the  only  new  varieties 
which  will  be  of  value  in  the  future  will  be  those  that  are  primarily 
of  superior  quality  for  shelling  purposes.  Yield  must  take  second 
place. 

"Well  known  varieties  are  not  only  in  heavier  demand  in  the  prin- 
cipal markets,  but  they  invariably  bring  much  better  prices  than 
the  newer  varieties.  In  some  years,  when  the  domestic  erop  of  a  given 
variety  is  light  and  the  demand  good,  it  is  possible  to  unload  poorer 
or  less  known  varieties  at  fairly  good  prices.  More  often,  however, 
they  are  a  drug  on  the  market. 

Owing  to  the  increasing  consumption  of  shelled  almonds  and  the 
probability  of  a  still  greater  increase  in  the  future,  growers  should 
arrange  future  plantings  with  a  view  to  supplying  the  best  shelling 
varieties.  At  the  present  time,  the  best  shelling  varieties  are  not 
ordinarily  the  heaviest  producers.  With  a  limited  production  they 
may  not  even  bring  as  large  returns  as  the  poorer  but  heavier  yielding 
varieties.  As  the  production  increases,  which  it  is  doing  very  rapidly, 
the  relative  value  of  the  best  shelling  varieties  will  increase  in  pro- 
portion and  they  may  be  sold  at  good  prices  when  it  will  be  impossible 
to  move  a  heavy  tonnage  of  a  poor  variety  at  a  profitable  price. 

Although  the  future  almond  markets  will  no  doubt  use  shelled 
almonds  very  largely,  there  will  always  be  a  limited  demand  for 
unshelled  almonds  for  use  in  the  holiday  trade  and  for  home  table  use. 
Unshelled  almonds  to  be  acceptable  for  such  purposes  must  be  large, 
attractive  nuts  with  light-colored,  clean-looking  shells,  soft  enough  to 
be  broken  with  the  hands.  The  kernels  must  be  well  filled  and  free 
from  gum.  The  I.X.L.  is  the  most  popular  and  highest-priced  nut 
for  this  purpose.  The  Ne  Plus  Ultra  ranks  next  because  of  its  attrac- 
tive outside  appearance  and  shape ;  one  of  the  principal  objections  to 
it  being  its  tendency  to  have  gummy  kernels.  The  Drake  is  another 
variety  in  demand  for  this  purpose.  It  is  moderately  large,  plump 
and  well  filled  with  a  good  quality  kernel,  and  while  not  as  attractive 
as  the  I.X.L.  or  Ne  Plus  Ultra,  it  is  popular  with  the  medium-priced 
trade.  A  certain  class  of  trade  prefers  the  Nonpareil  for  such  use, 
and  it  appears  to  be  growing  in  popularity  because  of  the  attractive 
kernel  and  the  ease  with  which  shelling  by  hand  is  accomplished. 


THE   ALMOND   IN   CALIFORNIA  65 

The  confectioners,  on  the  other  hand,  care  nothing  for  shell.  They 
want  a  medium  or  large  sized  kernel,  uniform  in  shape,  and  plump ; 
one  that  can  be  coated  smoothly  or  evenly  with  candy.  For  blanching 
and  salting  purposes,  the  kernels  must  be  large  and  smooth.  The  best 
California  variety  for  this  purpose  is  the  Nonpareil.  It  is  also  the 
best  nut  for  table  use  when  sold  shelled.  As  a  rule,  the  papershell 
varieties  are  the  best  for  shelling  because  of  the  large  percentage  of 
unbroken  kernels  which  may  be  obtained.  The  broken  kernels  and 
those  obtained  from  cheaper  and  less  desirable  varieties  are  used 
largely  by  the  bakers  and  almond-paste  manufacturers. 

The  planting  of  large  blocks  of  orchards  to  single  varieties  is  not 
a  wise  practice.  Planting  of  several  varieties  will  assist  greatly  in 
lengthening  the  harvest  season,  and  thus  enable  one  to  handle  large 
crops  with  fewer  men  and  less  equipment.  For  example,  the  four 
best  varieties — the  Nonpareil,  I.X.L.,  Ne  Plus  Ultra  and  Drake — ripen 
in  the  order  named;  the  Nonpareil  ripening  about  two  weeks  before 
the  I.X.L.,  the  Ne  Plus  Ultra  about  a  week  after  the  I.X.L.,  and  the 
Drake  about  two  weeks  after  the  Ne  Plus  Ultra.  Where  there  is 
danger  of  failure  of  varieties  to  set  fruit  due  to  frost  or  improper 
pollination  or  unfavorable  weather  conditions  during,  or  soon  after, 
blooming,  the  grower  is  more  likely  to  get  a  crop  from  some  variety 
if  several  are  planted  to  secure  a  succession  of  bloom  in  the  spring. 

The  principal  reason  for  interplanting  varieties  is  to  secure 
adequate  cross-pollination.  For  this  purpose  the  Ne  Plus  Ultra  and 
Drake  are  probably  the  best  to  use  as  pollinizers. 

Other  combinations,  as  indicated  on  page  6,  may  be  made  that 
will  be  satisfactory,  though  care  must  be  exercised  to  secure  varieties 
that  blossom  near  enough  together  to  be  effective.  Figure  26  shows 
the  effective  blossoming  period  for  fifteen  varieties. 

Adaptation  of  Varieties. — The  best  marketable  nuts  are,  as  has 
been  suggested,  few  in  number,  and  most  of  these  do  well  in  all  of 
the  principal  almond  districts  of  California.  Where  the  climatic  and 
soil  condition  are  equally  favorable  there  is  no  great  variation  in  their 
behavior,  but  owing  to  such  differences  it  has  been  found  that  certain 
varieties  are  better  adapted  to  some  districts  than  others. 

The  Nonpareil,  the  best  variety  known  at  the  present  time  for 
California  conditions,  bears  more  nearly  uniform  crops  from  year  to 
year  and  shows  a  wider  range  of  adaptation  than  any  of  the  other 
good  commercial  varieties.  It  has  proved  itself  to  be  satisfactory  in 
every  almond  district  in  the  state.  The  Drake  closely  approaches  the 
Nonpareil  in  this  respect.     The  I.X.L.  and  Ne  Plus  Ultra  are  the 


66  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

most  variable  in  their  behavior.  The  blossoms  of  the  two  varieties 
seem  to  be  more  tender  and  hence  more  liable  to  injury  under  un- 
favorable conditions ;  gumming  is  more  prevalent  near  the  coast,  and 
during  harvest  the  slower  ripening  and  opening  of  the  hulls  in  the 
more  moist  atmosphere  in  many  of  the  coast  valleys  causes  excessive 
darkening  and  sometimes  molding  of  the  shell.  The  Ne  Plus  Ultra 
does  its  best  on  comparatively  high,  well-drained  soils,  adjacent  to 
the  larger  streams  in  the  Sacramento  Valley,  such  as  the  lands  along 
the  Sacramento  River,  Putah  Creek,  Cache  Creek,  etc.,  though  it  also 
grows  and  produces  well  in  the  Banning  district  and  in  many  of  the 
foothill  sections  where  conditions  are  favorable.  The  I.X.L.  does 
best  on  the  foothills  surrounding  the  Sacramento  Valley,  notable  on 
the  west  side.  In  the  Banning  district  the  Ne  Plus  Ultra  seems  to 
be  a  better  producer  than  the  I.X.L.  Varieties  which  ripen  later  than 
the  Drake  should  be  avoided  in  the  Banning  district  because  of  the 
liability  to  damage  from  the  frequent  October  rains. 

There  are  a  number  of  different  varieties,  such  as  the  Eureka  and 
Jordan,  which  give  promise  of  filling  a  limited  place  in  the  markets 
but  which  have  not  yet  been  thoroughly  tested  throughout  the  state. 
The  Eureka  is  popular  with  confectioners  because  of  the  similarity 
in  shape  to  the  Jordan.  In  limited  quantities  the  demand  is  good. 
It  is  still  a  question  as  to  whether  it  would  hold  up  in  price  if  grown 
in  very  large  quantities.  The  Jordan  nut  is  of  excellent  quality  but 
in  California  the  trees  are  variable  in  vigor.  In  some  cases  the  trees 
make  unusually  large,  vigorous  growth  while  in  others  they  are  small 
and  apparently  stunted.  The  cause  of  this  has  never  been  adequately 
determined.  In  general,  the  Jordans  do  not  bear  sufficiently  heavy 
crops  to  make  them  pay  at  the  prevailing  low  prices.  The  chief 
reasons  for  the  low  prices  are  the  extreme  hardness  of  the  shell  and 
the  absence  of  satisfactory  methods  of  shelling.  The  invention  of  a 
satisfactory  machine  for  this  purpose  would  probably  make  it  pay  to 
plant  Jordans  in  much  larger  quantities. 

Other  varieties,  such  as  the  Texas,  have  been  sufficiently  tested  to 
show  them  to  be  well  adapted  to  most  districts,  but  they  are  not  to 
be  recommended  because  of  the  difficulty  experienced  in  marketing 
them  at  a  profit  in  large  quantities.  The  Texas  has  been  planted 
extensively  in  California  without  sufficient  justification.  It  was 
planted  because  of  its  value  as  a  pollenizer,  its  precocious  and  prolific 
bearing,  and  its  upright  habit  of  growth.  In  small  quantities  it  was 
sold  in  less  exacting  markets  as  a  Drake,  but  in  larger  quantities  there 
has  been  a  good  deal  of  objection  to  it  on  the  part  of  the  trade.     As 


THE   ALMOND   IN    CALIFORNIA 


67 


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68  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

the  bearing  trees  become  older  and  bear  heavier  crops,  the  nuts  tend 
to  become  smaller  and  the  shells  harder,  which  increases  the  difficulty 
of  selling.  From  the  standpoint  of  the  grower  as  well  as  the  market, 
the  lateness  in  ripening  is  very  objectionable.  The  California  Almond 
Growers'  Exchange  is  finding  it  harder  each  year  to  satisfactorily 
market  the  rapidly  increasing  tonnage  of  this  variety.  It  should, 
therefore,  be  avoided  in  new  plantings. 


SIZE    OF   ALMONDS 

Records  of  fourteen  varieties  of  almonds  grown  in  the  same 
orchard  under  similar  conditions  of  soil  and  culture  have  been  kept 
at  the  University  Farm  at  Davis,  for  the  years  1913  to  1916,  inclusive. 
These  trees  are  all  of  the  same  age,  except  the  Texas,  Peerless  and 
Harriott,  which  are  one  year  younger  than  the  others.  These  figures 
show  that  there  is  a  wide  variation  within  varieties  from  year  to  year, 
not  only  as  regards  size,  but  proportion  of  shell  to  whole  nut,  and  in 
the  proportion  of  double  kernels. 

Table  X  shows  the  variation  in  size  from  year  to  year,  as  indicated 
by  the  number  of  nuts  per  pound.  Five-pound  samples  of  each 
variety  were  used  to  determine  the  average  size : 

TABLE  X 
Number  op  Almonds  per  Pound  for  Years  1913  to  1916,  Inclusive 

Variety                        1913  1914  1915  1916  Average 

Nonpareil  256  240  224  223  236 

I.X.L 149  149  159  150  152 

Ne  Plus  Ultra 163  179  169  167 

Drake    189  132  131  130  145.5 

Languedoc    226  220  185  213  211 

Texas  182  171  165  173  173 

Reams  138  123  143  148  140.5 

Lewelling    154  150  158  139  150 

Peerless  118  127  134  124 

Princess 270  241  190  252  238 

California  232  211  206  216 

King    246  234  244  241 

Harriott    175  151  176  167 

Jordan    76  70  75  74 

The  value  of  an  almond  for  shelling  depends  not  alone  on  its 
relative  ease  of  cracking,  but  also  upon  the  percentage  of  kernel  to 
the  whole  nut  as  shown  in  table  XI : 


THE    ALMOND   IN    CALIFORNIA 


69 


TABLE  XI 

Percentage  of  Kernels  to  Whole  Nuts 

1913                     1914                     1915                     1916  Average 

Variety                   Percent             Percent            Percent            Percent  Percent 

Nonpareil    67.5                 65.0                 67.2                 67.0  66.6 

I.X.L 45.31               48.5                 60.6                 54.7  52.28 

Ne    Plus   Ultra 53.25               57.6                 58.5  56.45 

Drake  46.33               42.40               47.0                 42.2  44.48 

Languedoc  48.75               50.0                 49.4                 48.5  49.16 

Texas   43.75                45.0                  42.4                  44.4  43.89 

Beams    45.94               42.5                  49.25                43.4  45.27 

Lewelling  43.44               48.8                 50.6                 45.0  46.96 

Peerless   36.0                 39.65               32.5  36.05 

Princess  65.0                  73.0                  70.6                  73.8  70.6 

California    71.2                  70.6                  69.5  70.43 

King  70.0                 72.0                 71.6  71.2 

Harriott  56.25               54.2                 50.6  53.68 

Jordan   25.0                 23.8                 26.9  25.23 

Double  kernels  are  particularly  undesirable  in  nuts  for  shelling 
because  of  tbe  irregular  shape  of  the  halves,  which  renders  them  unfit 

for  confectionery  or  bakery  purposes  where  whole  kernels  are  used. 
Table  XII  shows  the  percentage  of  double  kernels  by  number : 


TABLE  XII 
Percentage  of  Double  Kernels  for  Different  Varieties 

Variety                         1914  1915  1916  Average 

Nonpareil   1.09  1.96  6.10  3.05 

I.X.L 50  .50  .80  .60 

Ne  Plus  Ultra 4.30  5.76  12.06  7.37 

Drake 12.72  6.25  6.65  8.54 

Languedoc    99  .32  1.60  .97 

Texas  11.56  7.40  11.90  10.29 

Beams   9.92  13.79  4.82  9.51 

Lewelling   13.30  28.70  46.50  29.50 

Peerless  4.44  7.05  8.38  6.62 

Princess    83  .21  4.61  1.88 

California  00  .00  .097  .032 

King    -. 00  1.28  2.13  1.14 

Harriott    1.43  .40  .80  .8« 

Jordan    1.32  3.72  3.74  2.93 


70 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


METHODS   OF   CLASSIFICATION 

Almonds  are  classified  according  to  hardness  of  shell,  into  four 
classes : 

Papershell. — Those  almonds  having  a  thin,  papery  shell  which  may 
easily  be  broken  between  the  fingers  of  one  hand. 

Softshell. — Those  which  have  a  more  or  less  spongy  or  thin  shell 
which  may  be  broken  between  the  fingers  of  two  hands. 


.  .-.-^ 


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Fig.  2/ 


-Almond  varieties. 


Standardshcll. — Those  requiring  very  strong  pressure  of  the  hand 
or  the  use  of  a  nut-cracker  to  break.  These  may  have  a  spongy  or 
smooth  outer  shell. 

Hardshell. — Those  which  cannot  be  broken  by  hand  but  require  a 
sharp  blow  with  a  hammer  or  strong  pressure  with  a  nut  cracker  to 
crack  them. 

The  papershell  varieties  are  excellent  for  shelling  as  they  contain 
a  large  percentage  of  kernels  which  may  easly  be  obtained  whole.  The 
principal  objections  are  that  birds  are  particularly  fond  of  them  since 
they  can  crack  them  easily,  and  the  shells  are  often  poorly  sealed. 


T1II0    ALMOND   IN    CALIFORNIA 


71 


The  latter  fact  makes  it  difficult  to  prevent  worm  infestation  and  to 
prevent  the  penetration  of  sulphur  fumes  to  the  kernel  during  the 
bleaching  process.  As  a  result  practically  none  of  the  papershells 
are  bleached  but  are  sold  for  shelling  purposes. 

The  softshells  are  generally  more  attractive  for  table  use  because 
the  shells  are  more  perfect  and,  in  commercial  varieties,  are  brighter 
in  color  and  more  attractive.  The  shells  are  usually  well  sealed  and 
can  be  bleached  to  give  additional  brightness  with  less  danger  of  the 
fumes  penetrating  to  the  kernel  than  the  papershells. 


Fig.  28. — Almond  varieties. 


The  standardshells  have  the  greatest  range  in  character,  thickness 
and  hardness  of  shell.  For  table  use  they  are  sometimes  too  hard  for 
high-class  trade.  The  percentage  of  kernel  is  too  low  to  make  them 
very  attractive  to  the  retail  trade.  Of  this  class  of  almond  the  Drake 
is  probably  the  best  of  the  California  varieties.  Almond  varieties  of 
all  these  classes  are  shown  in  figures  27  and  28.  These  illustrations 
show  most  of  the  varieties  grown  to  any  extent  in  California  and 
others  that  have  attracted  much  interest  and  inquiry,  together  with 
the  European  Tarragona. 


72  UNIVERSITY    OF    CALIFORNIA — p:XPERIMENT    STATION 

BIBLIOGRAPHY 

Tkeat,  W. 

1890.     Almond   Culture.     Eeport  of   California  Board    of   Horticulture,   1900, 
pp.  72-78. 

Fuller,  A.  S. 

1890.     The  Nut  Culturist,  pp.  12-43.     Orange  Judd  Co.,  New  York. 

Coksa,  W.  P. 

1890.     Nut  Culture. in  the  United   States,  Embracing  Native  and  Introduced 
Species.    U.  S.  D.  A.,  Division  of  Pomology,  pp.  19-28. 

Colby,  Geo.  E. 

1898.     Analysis  of  California  Almonds.     University  of  California  Agr.   Exp. 
Sta.   Eeport   1895-1890;    1890-1897,  pp.   145-151. 

Fairchild,  David  G. 

1902.     Spanish  Almonds   and  Their   Introduction   into  America.     Bulletin   23, 
Bureau  of  Plant  Industry,  U.  S.  D.  A.,  pp.  7-14  and  8  plates. 

Dargitz,  ,T.  P. 

1909.     The   Almond   Commercially   Considered.     Proc.    30th    Cal.    State   Fruit 
Growers'  Convention,  pp.  04-71. 

Wickson,  E.  J. 

1914.     California  Fruits  and  How  to  Grow  Them.     7th  edition.,  pp.  424-430. 

Bailey,  L.  H.,  and  Wickson,  E.  J. 

1914.     Almond,  Standard  Cyclopedia  of  Horticulture,  vol.  I,  pp.  249-251. 

Hunt,  Thos.  F.,  and  Staff. 

1914.  Some  Things  the  Prospective  Settler  Should  Know.     Circular  121,  Cal. 

Agr.  Exp.  Station,  pp.  3,  8,  41-42. 

Taylor,  E.  H. 

1915.  Present  Status  of  the  Nut  Industry  in  California.     Proceedings  of  the 

Society  for  Horticultural  Science,  1915,  pp.  31-39. 
1915.     A    Symposium    of    California    Pomology:    The    Almond.      Proceedings 
American  Pomological   Society,   1915,  pp.   121-120. 

Pierce,  Geo.  W. 

1915.     The  Status  of  the  Almond  Industry  of  the  Pacific  Coast.     Proceedings 
American  Pomological  Society,  1915,  pp.  75-82. 

Steubenrauch,  A.  V.,  and  Taylor,  E.  H. 

1915.     Some   Lessons    from   the    California   Nut    Industry.      Proceedings    14th 
Ann.  Conv.  National  Nut  Growers'  Association,  1915,  pp.  90-93. 


